Hello there!
4(x + 6) = 5( x + 9) + 4x
We wanna start with the distributive property
(4)(x) + (4)(6) = (5)(x) + (5)(9) + 4x
4x + 24 = 5x + 45 + 4x
4x + 24 = 9x + 45
Subtract 24 on both sides
4x + 24 - 24 = 9x + 45 - 24
4x = 9x + 21
Subtract 9x on both sides
4x - 9x = 9x + 21 - 9x
-5x = 21
Divide both sides by -5
-5x/-5 = 21/-5
x = -21/5