At present, A is thrice as old as B. C is 5 years elder than B. The sum of the ages of A, B, C is 75 years. The ratio of the age of B five years ago to the age of A three years from now is:

A.

2 : 3

B.

1 : 4

C.

4 : 7

D.

1 : 5

Solution:

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