The selling price of 15 items equals the cost of 20 items. What is the percentage of profit earned by the seller?

Question: The selling price of 15 items equals the cost of 20 items. What is the percentage of profit earned by the seller?

Solution:
Given that,
The selling price of 15 items = the cost price of 20 items.

Let, cost price of 1 item = x
Then, cost price of 20 items = 20x

Therefore, Selling price of 15 items = 20x
So, selling price of 1 item = 20x/15 = 4x/3

∴ Profit per item = (4x/3) - x
= (4x - 3x)/3 = x/3

∴ Profit percentage = {x/3)/x} × 100%
= (100/3)%
= 33.3%