Carlos's restaurant check is for $24.50. If he wants to add a 17% tip, what total amount should he pay?

First, convert the 17% to an actual number that can be used in a calculation. For percents,this is always done by simply dividing the percent (in this case 17%) by 100%.So, the conversational term "17%" becomes 17% / 100% = 0.17 in terms of a real mathematical number.
Second, you need to find out what 17% of your $24.50 meal cost is.This is always done by multiplying 0.17 by $24.50

0.17 x $24.50=$4.16.
So, the amount of tip you are going to leave is $4.16.

This makes the total cost of your meal (to write on your charge slip or other payment)

$24.50 + $4.16 = $28.67.