What is the equation for this word problem?

Question

What would the equation for this problem be? Joel has twice as many CDs as Mariella has. Subtracting 7 from the number of CDs Joel has and dividing by 3 equals the number of CDs Blake has. If Blake has 25 CDs, how many CDs does Mariella have? 

Answer 1

Let J = number of CDs Joel has

Let M = number of CDs Mariella has

 

Joel has twice as many CDs as Mariella  ==>  J = 2M

Subtracting 7 from J and dividing by 3 = 25   ==>   (J-7) / 3 = 25