Question

I bought a number of books one day, four times of them on the next day, and eight times on the third day, In all I bought $78$ books. How many books did I buy on the second day?

• A. $6$
• B. $8$
• C. $16$
• D. $24$
• E. $36$

Answer 1

The correct option is D $24$

Let the number of books bought of the first day be $a$
Thus, number of books on second day $=4a$
and the number of books on third day $=8a$
Now, given $a+4a+8a=78$
$\Rightarrow 13a=78$
$\Rightarrow a=\frac{78}{13}$
$\Rightarrow a=6$
Thus, the number of books bought of second day $=4\times 6=24$