You can put this solution on YOUR website! Assume the age of Mary is x years old,so the age of Jack is (x+5) .After 4 years Mary will be (x+4),and Jack's age will be (x+5) + 4.So the sum of the ages after 4 years will be :(x+4) + (x+5) +4= 33 . Simplify the equation gives 2x+13 = 33 .so 2x=20, and x = 10 Mary's age.and 10 + 5 = 15 which is Jack's age. hope it help.