Let x = Adam's age.
Callum is 3/8 of Adam's age.
Therefore Callum's age is (3/8)x.
Ben is 4/5 of Adam's age.
Therefore Ben's age is (4/5)x.
Callum is 2 years younger than Ben, therefore
(3/8)x = (4/5)x - 2
Multiply through by 40.
15x = 32x - 80
-17x = -80
x = 4.706
Adam's age is 4 years, 0.706*12 months = 4 years, 8.5 months
Answer: 4 years, 8.5 months
