A person's present age is two-fifth of the age of his mother. After 8 years, he will be one-half of the age of his mother. How old is the mother at present?

A. 32 years

B. 36 years

C. 40 years

D. 48 years

E. None of these

Answer: Option C

Solution(By Examveda Team)

$$\eqalign{ & {\text{Let}}\,{\text{the}}\,{\text{mother's}}\,{\text{present}}\,{\text{age}}\,{\text{be}}\,x\,{\text{years}}{\text{.}} \cr & {\text{Then,}}\,{\text{the}}\,{\text{person's}}\,{\text{present}}\,{\text{age}} \cr & = {\frac{2}{5}x} \,\,{\text{years}} \cr & \therefore {\frac{2}{5}x + 8} = \frac{1}{2}\left( {x + 8} \right) \cr & \Rightarrow 2\left( {2x + 40} \right) = 5\left( {x + 8} \right) \cr & \Rightarrow x = 40 \cr} $$