3x - 9 = 23 - 5x
Note the equal sign. What you do to one side, you do to the other.
Isolate the x. First Add 5x to both sides, and add 9
3x (+5x) - 9 (+9) = 23 (+9) - 5x (+5x)
3x + 5x = 23 + 9
Combine like terms
8x = 32
Simplify. Isolate the x. Divide 8 from both sides
8x/8 = 32/8
x = 32/8
x = 4
4 is your answer for x.
hope this helps