57. Exemplar problems XXIII

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. Form the pair of linear equations for the above situation. Find the cost of a pen and a pencil box.

 

 

The cost of a pen is $Rs.$.

 

The cost of a pencil box is $Rs.$.