To solve this, you need to isolate the variable x, this means only one side of the equation should have the variable x. To do this, you need to do the opposite operation from what's given (if it's addition, use subraction; if it's multiplication, use division; these work vise versa)
Subtract 9 from both sides of the equation. This gives you 10x = 4x - 18.
Subtract 4x from both sides of the equation. This gives you 6x = -18.
