10x + =15 An equals sign after a plus sign does not make sense.
-12x =72 There is only one step to isolate x.
After that, you simplify the fraction.
If you do not understand how to get the x by itself on the lefthand side, then you are not ready for any of these exercises.
3(4-y) =5 (y+2)
4x/5 + 3/2 = 2x
1/6 -x/2 = x-5/3