A restaurant customer left $2.60 as a tip. The tax was 5% and the tip was 20% of the after tax cost. Which information is not needed to compute the bill after tax and tip? What was the total bill?

The tax rate is not needed

Total bill cost = $13

Step-by-step explanation:

Given that :

Tip left = 2.60

Tax = 5%

Tip left = 20% of after tax cost

To calculate the total bill amount, we do not need information about the tax rate.

Since the total amount paid = after tax amount

Tip left = 2.60 is equal to 20% the after tax cost

Let after tax amount = t

Then,

20% of t = 2.60

(20/100) * t = 2.60

0.2t = 2.60

t = 2.60/0.2

t = 13

Hence, total bill is $13