By selling 80 oranges a man gains a cost price of 20 oranges. What is the gain percentage? To solve this tricky question, let the cost price (CP) of an orange is 1 Rs.
Now CP of 80 oranges = 80 Rs………..(1)
And we know that
Profit= SP (selling price) - CP (cost price)
Here;
Profit = SP of 80 oranges - CP of 80 oranges…….(2)
{Here profit is already given that is CP of 20 oranges }
By (2);
CP of 20 oranges = SP of 80 oranges - CP of 80 oranges