First, you want to get the parenthesis out of the equation. To do that, you have to distribute the 5 to get 7+5x-15=22.
Next you want to join like terms by saying -8+5x=22
After that, we want to get the plain numbers together so we add 8 to 22 to get 5x=30.
We want to get the x alone so we divide 30 by 5 to get x=6.
Hope this helped!