Question 603760
Ali's age = A
Ed's age = E


A = 2E


A - 4 = 4*(E -4)
2E - 4 = 4E - 16
16 - 4 = 4E - 2E
12 = 2E
E = 12/2 = 6


A = 2E = 2*6 = 12


6 + x + 12 + x = 66
18 + 2x = 66
2x = 66 - 18
2x = 48
x = 48/2 = 24


so 24 years later the sum of their ages will be 66