The ratio of the ages of A and B, 8 years ago, was 5 : 7. The ratio of their ages, 8 years from now, will be 9 : 11. If the present age of C is 13 years less than that of B, and the present age of D is 8 years less than that of the age of A, then the sum of the present ages of C and D, in years, is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 43.
(A - 8)/(B - 8) = 5/7
⇒ 7A - 5B = 16 .....(1)
(A + 8)/(B + 8) = 9/11
⇒ 11A - 9B = -16 .....(2)
From (1) and (2), we get A = 28 and B = 36
C = B - 13 = 36 - 13 = 23
D = A - 8 = 28 - 8 = 20
C + D = 23 + 20 = 43 years