What is the total cost for a $20 haircut with a 15% tip

So you are going to pay $20 and then a 15% tip on top of the 20.

And the 15% tip is 15% of $20.

To do less work, you can basically do 115% of 20 to find out the total cost instead of doing 15% of 20 and then adding that to 20.

Saying that x is the final price to pay, and converting the percents to fractions we get:



Simplify that:



And simplifying that further, you get the final answer as:



So you have to pay $23 after the tip :)