One day, Ted needed a pen. When he reached the store, he found that the shopkeeper had lost his list on which he had written how many notebooks he sold. But he had the list of pens and his total profit.
For each notebook, he gets Rs4 as profit and for each pen he loses 20 paisa. The total profit he made was Rs40. And he sold 100 pens during that period. Find the number of notebooks sold during that period. [Assume he only sold notebooks and pens during that period; Answer in terms of a number]
Loss on selling 1 pen = 20 paisa = −Rs0.2
So, loss on selling 100 pens =Rs((−0.2)×100)= −Rs20
Total gain = Profit earned on notebooks + Loss incurred on pens
So, Profit earned on notebooks = Total gain - Loss incurred on pens
So, notebooks sold = Profit earned on notebooks/ Profit per notebook