A tradesman sold an article at a loss of 20%. If the selling price had been…

Step-by-Step Solution

To find the cost price, we can use the relationship between the initial loss and the final gain.

1. Define variables:

   • Let the cost price be 'a'.

   • A loss of 20% means the initial selling price is 80% of 'a', or 0.8a.

2. Set up the equation:

   • If the selling price is increased by Rs. 120, the new selling price is 0.8a + 120.

   • This new selling price results in a 10% gain, which is 110% of 'a', or 1.1a.

   • So, 0.8a + 120 = 1.1a.

3. Solve for 'a':

   • 120 = 1.1a - 0.8a

   • 120 = 0.3a

   • a = 120 / 0.3

   • a = Rs. 400.