Question

A restaurant customer left ​$1.40 as a tip. The tax was 5 % and the tip was 20​% of the cost including tax.
a. Which information is not needed to compute the bill after tax and​ tip?
b. What was the total​ bill?

Answer 1

a. The 5% tax rate is not needed — because the tip is 20% of the amount after tax, the subtotal (cost including tax) can be found directly from the tip.

b. Tip = 20% of subtotal, so subtotal = 1.40 / 0.20 = $7.00. Total = subtotal + tip = 7.00 + 1.40 = $8.40.