Question

Q. Present ages of A and B are in the ratio 7: 9 respectively. After 5 years this ratio becomes 9: 11. Then the difference between their present ages is:

• A. 4 years
• B. 5 years
• C. 8 years
• D. 7 years

Answer 1

The correct option is B 5 years

Explanation:

Let the present age of A and B be x and y.

So, given ratio = 7 : 9

$\frac{x}{7}=\frac{y}{9}$

$9x-7y=\mathrm{0..........}\left(1\right)$

After 5 years the ratio $=9:11$

$x+\frac{5}{9}=y+\frac{5}{11}$

$11x-9y=-\mathrm{10........}\left(2\right)$

After solving eq (1) and eq (2),

we get $x=17.5$ years and $y=22.5$ years

Difference $=22.5-17.5=5$ years