Question 1108538
Henry's age = x
Dad's age = x + 18

After 10 years....

Henry's age = x + 10
Dad's age = x + 18 + 10

(x + 18) + 10 = (x + 10) * 2
x + 28 = 2x + 20
x - 2x = 20 - 28
(-x) = (-8)
x = 8

Henry's present age = x = 8
Dad's present age = x + 18 = 8 + 18 = 26