Restaurant Math Word Problems: Tax, Tip and Splitting the Bill
Subtotal → tax → tip → split. Add the menu prices, multiply the subtotal by the tax rate, work out the tip on the subtotal before tax, then divide. The order matters: a coupon comes off before tax, and the tip is usually figured on the price before both the tax and the coupon.
Restaurant bill problems show up in middle-school percent units, consumer math courses and hospitality classes, and they all build from the same four steps. The worked problems below go from a single bill to splitting a check fairly and pricing a catered party. If you are working on the restaurant's side of the menu — what a dish costs to make and what to charge — see food cost percentage word problems.
The Formulas
Tax = subtotal × tax rate
Tip = subtotal × tip rate (before tax)
Total = subtotal + tax + tip
Each person's share = total ÷ people
Level 1: The Subtotal
You order a burger for $12.50, fries for $4.25, a salad for $9.75 and two sodas at $2.50 each. What is the subtotal?
$12.50 + $4.25 + $9.75 + (2 × $2.50) = $31.50.
The usual slip is counting the soda once. Multiply anything ordered more than once before adding.
Level 2: Sales Tax
Sales tax is 8%. What is the tax on that $31.50 bill, and the total before tip?
Tax = $31.50 × 0.08 = $2.52. Total = $31.50 + $2.52 = $34.02. Or in one step: $31.50 × 1.08 = $34.02.
A $48.80 order is taxed at 6.25%. What is the total?
$48.80 × 0.0625 = $3.05. Total = $51.85. Turn the percentage into a decimal by moving the point two places: 6.25% = 0.0625.
Level 3: The Tip
You leave an 18% tip on the $31.50 subtotal. What is the tip, and what do you pay in all?
Tip = $31.50 × 0.18 = $5.67. Total = $31.50 + $2.52 tax + $5.67 tip = $39.69.
Tipping on the after-tax $34.02 instead gives $6.12 — 45 cents more. Etiquette guides generally say to tip on the amount before tax, and most textbook problems do the same unless they say otherwise.
For mental math, find 10% by moving the decimal point one place ($3.15), double it for 20% ($6.30), or take half again for 15% ($3.15 + $1.58 = $4.73).
Level 4: Splitting the Bill
Four friends have a $86.40 subtotal. Tax is 7.5% and they tip 20% before tax. They split evenly. How much does each pay?
Tax = $86.40 × 0.075 = $6.48. Tip = $86.40 × 0.20 = $17.28. Total = $86.40 + $6.48 + $17.28 = $110.16.
Each pays $110.16 ÷ 4 = $27.54.
Same bill, but they pay for what they ordered: $28.00, $19.50, $22.40 and $16.50. How much does each pay, including their share of tax and tip?
Every dollar ordered costs $110.16 ÷ $86.40 = 1.275 dollars once tax and tip are added (1 + 0.075 + 0.20).
| Ordered | × 1.275 |
|---|---|
| $28.00 | $35.70 |
| $19.50 | $24.86 |
| $22.40 | $28.56 |
| $16.50 | $21.04 |
| $86.40 | $110.16 |
The shares add back to the total, which is the check that the multiplier was right.
Level 5: Coupons and Combo Deals
A $45.00 meal has a 20% off coupon. Tax is 8%, and you tip 20% on the original price. What do you pay?
Discounted subtotal = $45.00 × 0.80 = $36.00. Tax on the discounted price = $36.00 × 0.08 = $2.88, so $38.88. Tip on the original $45.00 = $9.00.
Total = $38.88 + $9.00 = $47.88. The coupon lowers what the restaurant charges, not the work the server did, which is why the tip is usually figured on the full price.
A combo is $11.99. Bought separately, the burger is $8.49, fries $3.29 and a drink $2.19. How much does the combo save, and by what percent?
Separately: $8.49 + $3.29 + $2.19 = $13.97. Saving = $13.97 − $11.99 = $1.98. Percent saved = $1.98 ÷ $13.97 = 14.2% — divided by the original price, not the combo price.
Level 6: Catering Priced Per Person
A buffet costs $24 per person for 35 guests. The caterer adds an 18% service charge, and 7% sales tax applies to the food only. What is the total, and what does it come to per guest?
Food = 35 × $24 = $840.00. Service charge = $840 × 0.18 = $151.20. Tax = $840 × 0.07 = $58.80.
Total = $840.00 + $151.20 + $58.80 = $1,050.00, or $30.00 per guest — 25% above the advertised $24.
Whether tax applies to a service charge depends on the state, so real quotes vary; in a word problem, follow what the problem says. Working out how much food to make for those 35 guests is a different problem — see the catering pan calculator.
Quick Reference
| Step | Do this | Watch for |
|---|---|---|
| Subtotal | Add every item × quantity | Items ordered more than once |
| Coupon | Subtotal × (1 − discount) | Applies before tax |
| Tax | Discounted subtotal × rate | Rate as a decimal: 7.5% = 0.075 |
| Tip | Subtotal before tax × tip rate | Usually on the pre-coupon price |
| Split by order | Each order × (total ÷ subtotal) | Shares must add back to the total |
| Percent saved | Saving ÷ original price | Not ÷ the sale price |
More Practice
The kitchen math problem generator makes fresh restaurant bill problems with the working shown, along with unit price, cost per serving and food cost problems. For the grocery side of the same skills, see unit price word problems and cost per serving word problems; the complete culinary math guide collects every type.
Frequently Asked Questions
Do you tip before or after tax?
Etiquette guides generally say to tip on the amount before tax, and most textbook problems do the same unless they say otherwise. Tipping after tax adds only a little — 45 cents on a $31.50 bill at 18%.
How do you work out an 18% tip quickly?
Find 10% by moving the decimal point one place, double it for 20%, then take off a tenth of that. On $31.50: 10% is $3.15, 20% is $6.30, and 18% is $6.30 − $0.63 = $5.67.
How do you split a bill with tax and tip by what each person ordered?
Divide the full total by the subtotal to get a multiplier, then multiply each person's order by it. With 7.5% tax and a 20% tip the multiplier is 1.275, so a $28.00 order becomes $35.70.
Is a coupon taken off before or after tax?
Before. Sales tax is charged on what you actually pay for the food, so take the discount off first, then add tax to the lower price.