A trader marks his goods 50% above cost. He wants the discount percentage and his profit percentage to be the same number. What must that number be?

Explanation

1. 01

   Take CP = ₹100, so MP = ₹150. Let the discount be x%.

2. 02

   SP = 150$(1 - x/100)$, and it must also equal 100$(1 + x/100)$.

3. 03

   $150 - 1.5x = 100 + x$, so $2.5x = 50$ and $x = 20$.

4. 04

   Check: 20% off ₹150 gives ₹120, a profit of 20%.