Eight years ago, the ratio of the ages of A and B was 9: 10. The ratio of their ages 4 years from now will be 12: 13. If the age of C is 4 years less than the present age of A, then what is the present age (in years) of C?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 40.
Let A = a, B = b8 yrs ago: (a−8)/(b−8) = 9/10 → 10a − 9b = 8 …(1)
4 yrs ahead: (a+4)/(b+4) = 12/13 → 13a − 12b = −4 …(2)
Solve (1) & (2):
×12: 120a − 108b = 96
×9: 117a − 108b = −36
Subtract: 3a = 132 ⇒ a = 44
C = a − 4 = 40