Ratio is 6:5, the sum is 55.
6x + 5x = 55
11x = 55
x = 55/11
x = 5
Their ages now are:
6*5 = 30 years old
5*5 = 25 years old
Lets find their ages for the ratio of 8:7
Let y = years:
30 +y / 25 +y = 8/7
Cross multiply:
8(25 +y) = 7(30 +y)
200 + 8y = 210 + 7y
y = 10
The answer is C.10
