SOLUTION: the ratio of Binoy’s and Alisha’s present age is 5 : 6. Three years hence the ratio of their ages will be 6 : 7 respectively. What was Alisha’s age eight years ago?

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Question 984160: the ratio of Binoy’s and Alisha’s present age is 5 : 6. Three years hence the ratio of their ages will be 6 : 7 respectively. What was Alisha’s age eight years ago?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
system%28b%2Fa=5%2F6%2C%28b%2B3%29%2F%28a%2B3%29=6%2F7%29

Goal is solve for a-8.

b=5a%2F6
-
7%28b%2B3%29=6%28a%2B3%29
7b%2B21=6a%2B18
7b-6a=-3
6a-7b=3
substitute for b.
6a-7%285a%2F6%29=3
36a-35a=18
a=18------Current age for Alisha

She was 10 years of age, 8 years ago.