Question

The cost of 4 pens and 4 pencils boxes is Rs. 100. Three times the cost of a pen is Rs. 15 more than the cost of a pencil box. Form the pair of linear equations for the above situation. Find the cost of a pen and a pencil box.

Answer 1

Let the cost of a pen Rs x and the cost of a pencil box be Rs. Y.
Then, by given condition,
`4x+4y=100 rArr x +y=25 " " ...(i)`
and `" " 3x=y+15`
`rArr " " 3x-y=15 " " ...(iii)`
On adding Eqs. (i) and (ii). We get
4x=40
`rArr " " x=10`
By substituting x=10, in Eq. (i) we get
y=25-10=15
Hence, the cost of a pen and a pencil box are Rs 10 and Rs 15, respectively.