Question

The cost of $4$ pens and $4$ pencil boxes is Rs $100$. Three times the cost of a pen is Rs $15$ more than the cost of a pencil box. The cost of a pen and a pencil box respectively are

• A. Rs $15$ and Rs $8$
• B. Rs $10$ and Rs $15$
• C. Rs $12$ and Rs $10$
• D. Rs $16$ and Rs $12$

Answer 1

The correct option is B Rs $10$ and Rs $15$

Let the cost of a pen and a pencil be $x$ and $y$ respectively.
$4x+4y=100$
$x+y=25$ ...(1)
$3x=y+15$
$3x-y=15$ ...(2)
Adding (1) and (2), we get
$4x=40$
$x=10$
Substitute $x=10$ in equation (1) to get $y=15$.