### A librarian purchased 50 storybooks for his library. But he saw that he could get 14 books more by spending Rs. 76 more but per book average becomes Rs. 1 less. The average price (in Rs.) of each book he bought, was :

A. 15

B. 25

C. 20

D. 10

Let the average price of 1 book = Rs. 1 $\begin{array}{l}\text{According to the question,}\\ \begin{array}{l}\Rightarrow\left(\Large\frac{50x+76}{50+14}\right)=(x-1)\\ \Rightarrow\left(\Large\frac{50x+76}{64}\right)=x-1\\ \Rightarrow50x+76=64x-64\\ \Rightarrow140=14x\\ \Rightarrow x=Rs.10\end{array}\end{array}$ Therefore average price of 1 book = Rs. 10