A shopkeeper expects a gain of 25% on his cost price. If in a week, his total revenue was 320 taka, what was his profit in taka?

Question: A shopkeeper expects a gain of 25% on his cost price. If in a week, his total revenue was 320 taka, what was his profit in taka?

Solution:
Let cost price = C taka.
Gain = 25% of cost
= 25% × C
= 0.25C

∴ Selling price = C + 0.25C = 1.25C
Given that,
selling price = 320 taka.
According to the question,
1.25C = 320
⇒ C = 320/1.25
∴ C = 256 taka.

Profit = Selling price - Cost price = 320 - 256 = 64 taka