Given: The age of Mr X = 40 years The age of Mr Y = 60 years Calculation: Let t years ago their ratio of age was 3 ∶ 5 Now, t years ago The age of Mr X =(40–t) years The age of Mr Y=(60–t) years Now, A/Q (40–t)/(60–t)=3/5 ⇒5(40–t)=3(60–t) ⇒200–5t=180–3t ⇒2t=20 ⇒ t = 10 years ∴ The required ratio of their age was 10 years ago