the selling price of 15 items equals the coast of 20 items.what is the percentage profit earnd by the seller?

To find the percentage profit earned by the seller, we need to compare the selling price to the cost price.

Let's assume the cost price of each item is "C" taka, and the selling price of each item is "S" taka.

According to the problem, the selling price of 15 items equals the cost of 20 items:

15S = 20C

Now, let's calculate the profit per item, which is the difference between the selling price and the cost price:

Profit per item = S - C

To find the percentage profit, we'll use the formula:

Percentage Profit = (Profit per item / Cost Price) * 100

We already have the equation 15S = 20C. Let's solve it for S:

S = (20C) / 15

Now, substitute this value of S into the profit per item equation:

Profit per item = ((20C) / 15) - C

To simplify further:

Profit per item = (20C/15) - (15C/15)

Profit per item = (20C - 15C) / 15

Profit per item = 5C / 15

Now, calculate the percentage profit:

Percentage Profit = (Profit per item / Cost Price) * 100

Percentage Profit = ((5C / 15) / C) * 100

Percentage Profit = (5/15) * 100

Percentage Profit = (1/3) * 100

Percentage Profit = 33.33%

So, the seller earned a percentage profit of 33.33%.