Present ages of A and B are in the ratio 5 : 6 respectively. After seven years this ratio becomes 6 : 7. Then the present age of A in years is = ?

Answer: Option A

Let the age of A & B = 5x and 6x years
According to question,
$$\begin{array}{rl}& \frac{5x+7}{6x+7}=\frac{6}{7}\\ & 35x+49=36x+42\\ & x=7\\ & \text{A’s Present age}=5x\\ & =5\times 7=\text{35 years}\end{array}$$