The ratio of Alan's age to Ben's age is 5 : 3 now. 6 years ago,
the ratio was 7: 3. How old was Ben 6 years ago?
a/b = 5/3
(a-6)/(b-6) = 7/3
or
3a = 5b
3(a-6) = 7(b-6)
3a-18 = 7b-42
5b-18 = 7b-42
24 = 2b
b = 12
so a = 5/3 * 12 = 20
the ratio was 7: 3. How old was Ben 6 years ago?
(a-6)/(b-6) = 7/3
or
3a = 5b
3(a-6) = 7(b-6)
3a-18 = 7b-42
5b-18 = 7b-42
24 = 2b
b = 12
so a = 5/3 * 12 = 20