10 years ago , the ratio of age of A to that of B was 4 : 5. Ten years hence, the ratio of age of A to that of B will be 6 : 7. If at present C is 10 years younger than B , then what will be ratio of present age of A to that of C ?
Answer & explanation
Correct answer: option 1
( 10 years ago ) A : B
4 : 5
present age of A = 4x + 10 , present age of B = 5x + 10
according to question , after 10 years
A : B
6 : 7
i.e. \(\frac{4x\;+\;20}{5x\;+\;20}\) = \(\frac{6}{7}\)
28x + 140 = 30x + 120
2x = 20
x = 10
as , A's present age = 4x + 10
A's present age => 40 + 10 = 50
B's present age => 5×10 + 10 = 60
It is given that C is 10 years younger than B
So, C's present age => 60 - 10 = 50
Ratio of A : C
50 : 50
1 : 1