Hello Diamond,
Let's get started. Since you've like terms on the left hand side of the equation, so subtract them.
18x - 24x = 1/2 (original equation)
-6x = 1/2
divide both sides by -6
(-6x)/-6 = (1/2)/-6
x = (1/2) * (-1/6)
x = -1/12 (answer)
Hope this helps. If you need any other help you can ask, I'll be glad to help or any other tutor will guide you.