Respuesta :

3x - 15 = 39
+ 15 +15

3x = 54 (divide by 3 on each side)

X = 18

Answer:

X=18

Step-by-step explanation:

To isolate X you need to get rid of the -15 to do that you can add 15 on both sides of the equation resulting in 3x=54 now you need to divide both sides by 3 to get x on its own which is X=18.