Question

15 liters increased by 60 percent

Answer 1

Initial quantity given in the question = 15 liters
Percentage of increase in the initial quantity = 60%
Then
Amount of increase in the initial quantity = (60/100) * 15
                                                                 = (6/10) * 15 liters
                                                                 = 90/10 liters
                                                                 = 9 liters
Then
Total quantity after increase = 15 + 9 liters
                                             = 24 liters
So the total quantity after increase of 60% becomes 24 liters. I hope the procedure is simple enough for you to understand. You can use this method in future for solving similar type of problems and you will surely get to the perfect and desired result. Only be careful about the calculation part.

Answer 2

15 * 60/100 = 9 liters

15 + 9 = 24liters