Question 18658
Try this.

A = Aaron's age now.
J = Jack's age now.
Write two equations from the problem description.

A = 2J Aaron is twice Jack's age.
(A-3) + (J-3) = 45 The sum of their ages 3 years ago = 45 Simplify.
A + J - 6 = 45  Add 6 to both sides.
A + J = 51 Substitute A = 2J
2J + J = 51
3J = 51 Divide both sides by 3.
J = 17 years.
A = 2J = 2(17) = 34 years.