A son's present age is two-fifth of the age of his mother. After 5 years, his age will be half the age of his mother. How old is his mother at present?

Correct option is C

Given:

The son's present age is two-fifth of the mother's present age.

After 5 years, the son's age will be half the mother's age.

Solution:

Let be the present age of Mother is = $$x$$

then the present age of Son is (According to question) = $$\frac{2x}{5}$$

After 5 years, the son's age will be half the mother's age.

​$$(x+5)=(\frac{2x}{5}+5)\times2$$​

$$(x+5)=(\frac{2x+25}{5})\times2$$

​​$$(x+5)\times5=({2x+25})\times2$$ 

$$5x+25=4x+50$$

$$5x-4x=50-25$$

$$x=25$$ (The present age of Mother)

Thus the correct answer is (C)