Eight years ago, the ratio of ages of A and B was 9 10. The ratio of their ages 4 years from now will be 12 : 13. What is the age (in years) of C now,if his age is 6 years more than that of A ?

let the ages of A and B eight years ago be 9x and 10x respectively

present age of A and B after 8 years will be

9x+8, 10x+8

therefore age of A and B after 4 more years will be 9x+12, 10x+12

and the given ratio of ages after 4 years is 12:13 so equating this we get

$$\frac{9x+12}{10x+12}$$ = $$\frac{12}{13}$$ solving this we get x=4

so age of A 8 years ago is (9)(4) = 36 

so age of A after 8 years is 36+8=44

as, we know C is 6 years elder than A hence age of C is 44+6=50