Question: -2(x-9)=-24
All you have to do is solve for the variable x.
First of all, you want to get (x-9) all by itself on one side, alone from all the other numbers. (although technically 9 is a number but we'll just ignore that for now)
Divide by the number -2 on both sides in order to isolate (x-9). The result is x-9=12 (no parentheses for x-9 because it is isolate and there is no other number other than that). Negatives cancel to become positive.
Now, isolate x all by itself.
Add 9 to both sides in order to isolate x. The result is x=21.