If the selling price is tripled, the profit becomes eight times. Find the profit percent.

Question: If the selling price is tripled, the profit becomes eight times. Find the profit percent.

Solution:
Let,
The cost price be Tk.100 and sell price be Tk. x,

Then,
The profit is = (x - 100)

Now, The sell price is doubled, then the new sell price is 3x
New profit is = (3x - 100)

ATQ,
8(x - 100) = 3x - 100
⇒ 8x - 800 = 3x - 100
⇒ 8x - 3x = 800 - 100
⇒ 5x = 700
∴ x = 140

Then, the Profit = (140 - 100) = 40
Hence the profit percentage is = (40/100) × 100%
= 40%