If you would like to solve 75% of x peaches is 15 peaches, you can calculate this using the following steps:
75% of x peaches is 15 peaches
75% * x = 15
75/100 * x = 15 /*100/75
x = 15 * 100 / 75
x = 20 peaches
Result: 75% of 20 peaches is 15 peaches.