45. Jen and Sarah want to leave a 20% tip based on the costs before tax. Then how much tip should they leave? The amount without tax is 28.00 dollars and the amount with tax is 29.68 dollars. Since we only need to amount without tax, we need to calculate 20% of 28.oo dollars. => 28.00 dollars is the amount => 20% = 20% / 100% = .20 Now, let’s multiply: => 28.00 * .20 = 5.6 dollars. Now, they will have to leave 5.6 dollars for tip.