Distribute 3 to all terms within the parenthesis
3(x + 1) = 3x + 3
Distribute 5 to all terms within the parenthesis
5(x - 2) = 5x - 10
3x + 3 = 5x - 10 + 7
Simplify
3x + 3 = 5x (-10 + 7)
3x + 3 = 5x - 3
Isolate the x. Subtract 3 from both sides and 5x from both sides
3x (-5x) + 3 (-3) = 5x (-5x) - 3 (-3)
3x - 5x = -3 - 3
Simplify
-2x = -6
Isolate the x. Divide -2 from both sides
-2x/-2 = -6/-2
x = -6/-2
x = 3
3 is your answer for x.
hope this helps