Explanation:

- Let's assume the cost price of the goods is $100.

- The merchant marks the sale price at 42% above the cost price:

- Marked Price = $100 + 42% of $100 = $142.

- A 15% discount is applied to the marked price:

- Selling Price = $142 - 15% of $142 = $120.70.

- The profit made by the merchant is Selling Price - Cost Price:

- Profit = $120.70 - $100 = $20.70.

- To find the percentage profit:

- Percentage Profit = ($20.70 / $100) * 100 = 20.7%.

- When rounded off to the nearest integer, the percentage profit is 21%.

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