How to compute this?

Question

You and your family go to dinner at a local restaurant in Rexburg, Idaho and your online banking report shows that the total dinner bill (food, tax, and tip) was for $38. Suppose that you did not keep your receipt, but you remember you paid a 10% tip for the service.

 

What was your bill (food and tax) prior to calculating the tip? (tip was paid on the total of food and tax)

Answer 1

(Food & Tax cost) + Tip = Total Paid

Call Food & Tax cost F

Tip = .10*F (10% of Food & Tax cost)

Total Paid = 38

(Food & Tax cost) + Tip = Total Paid

F + .10*F = 38

1.10F = 38

F = 34.55

$34.55 was the pretip bill