HELP I NEED SOMEONE TO FIGURE THIS OUT!!

Question

A restaurant customer left

​$0.70

as a tip. The tax was

5%

and the tip was

10​%

of the after tax cost. Which information is not needed to compute the bill after tax and​ tip? What was the total​ bill?

Answer 1

Lets say the bill before tax was b

Then bill after tax = 1.05b

Tip = 0.10 x 1.05b = 0.70

So the bill before tax is (0.70 / 0.10 / 1.05) = $ 6.67

Bill after tax and tip = b x 1.05 x 1,10 = $ 7.70

We actually don't need the tax rate here

Because after tax cost = 10 x 0.70 = 7.00

And tip is 0.70 so total = 7 + 0.70 = 7.70