The ratio of the ages of A and B is 4:5. After 6 years, the ratio becomes 5:6. What will be the ratio of their ages 6 years ago?
Show answer & explanation
Correct answer: A
Explanation
Given:
A : B = 4 : 5
After 6 years, A : B = 5 : 6
Let:
A = 4x
B = 5x
After 6 years:
(4x + 6) / (5x + 6) = 5 / 6
6(4x + 6) = 5(5x + 6)
24x + 36 = 25x + 30
x = 6
A = 4 × 6 = 24
B = 5 × 6 = 30
6 years ago:
A = 24 − 6 = 18
B = 30 − 6 = 24
Ratio = 18 : 24 = 3 : 4