If you would like to solve 4 + 3/5 * (15 + 2x) = 25 for x, you can do this using the following steps:
4 + 3/5 * (15 + 2x) = 25
3/5 * (15 + 2x) = 25 - 4
9 + 6/5 * x = 21
6/5 * x = 21 - 9
6/5 * x = 12 /*5/6
x = 12 * 5/6
x = 10
The correct result would be x = 10.