Given∶ Age difference between Shaad and Noor is of 20 years. Ratio of their ages before 4 years = 2 ∶ 1 Formula Used∶ If a∶b=c∶d Then product of Extremes = Product of means ⇒a×d=b×c Calculation∶ Let Shaad’s present age be ‘x’ years and Noor’sage be ‘y’ years. So, x−y=20 ----(1) 4 years before, Shaad’s age was (x−4) years Noor’s age was (y−4) years According to question, (x−4)∶(y−4) years = 2 ∶ 1 ⇒x−4=2y−8 ⇒x−2y=−4 ----(2) Subtracting eq (1) from (2), we get, y=24 Put y=24 in eq (1) x−y=20 ⇒x−24=20 ⇒x=24+20=44 ∴ Shaad’s present age is 44 years and Noor’s present age is 24 years.