The ratio of the present ages of X and Y is 3 : 4. Five years ago, the ratio of their ages was 5 : 7. What is the present age of Y?

Correct option is D

Given:

The ratio of the present ages of X and Y is 3 : 4.

Five years ago, the ratio of their ages was 5 : 7.

Solution: 

Let the present age of X = 3x 

Present age of Y = 4x 

According to the question, 

$$\frac{3x - 5 }{4x - 5} = \frac{5}{7}$$ 

21x - 35 = 20x - 25 

x = 10 

Then, 

Present age of X = 3x =  3$$\times 10$$ = 30 years

Present age of Y = 4x = $$4\times 10 = 40$$ years ​