Problem: A shop keeper prices p toys at Rs. q per toy. If the cost of each toy is increased by Rs. r, then find how much more money will be earned by the shop owner after selling p toys?
Effort : Let the Old cost price of each toy be Rs. $x$. Then Selling price of each toy is Rs. $q $ $(>x)$. New cost price of each toy is Rs. $x+r$. New cost price of $p$ toys is Rs. $p(x+r)$ and the selling price of $p$ toys is Rs. $pq$.
I am stuck here. By the way is my approach correct?
Updated:
Old cost of each toy is Rs. $q$.
Old cost of $p$ toys is Rs. $pq$.
The cost of each toy is increased by Rs. $r$. So the new cost of each toy becomes $q+r$.
The new cost of $p$ toys is Rs. $p(q+r)$.
After selling $p$ toys, the shop keeper will earn Rs. $p(q+r)-pq=pr$.