Melisa and Jennifer threw a fiftieth birthday party for their father at a local restaurant. While the bill came, Melisa added a 15% tip of $42. Jennifer said in which the service was wonderful and they should leave a 20% tip instead. How much is a 20% tip?

To ?nd 20%, add 5% to 15%. Because 15% is known to be $42, 5% can be found by dividing $42 by 3 (15% ÷ 3 = 5%); $42 ÷ 3 = $14. To ?nd out 20%, add the 5% ($14) to the 15% ($42); $14 + $42 = $56; 20% is $56.