An item is sold for 15,000 at a loss of 20%. Its cost price was:

1. A loss of 20 per cent means the sale price is 80 per cent of the cost price. 2. So 80 per cent of the cost price = 15000. 3. One per cent is 15000 / 80 = 187.5. 4. The cost price is 100 x 187.5 = 18750. 5. Adding 20 per cent to 15000 gives 18000, which is wrong because the loss was measured on the cost, not on the sale price. _Source: NCERT Class 8 Maths, Ch 7 'Comparing Quantities', S7.1 Recalling Ratios and Percentages_