The selling price of 21 articles is equal to the cost price of 18 articles. Find the loss percent?.

Step 1: Let's assume the cost price of 1 article is $1. Therefore, the cost price of 18 articles would be$18.

Step 2: According to the problem, the selling price of 21 articles is also $18.

Step 3: Now, let's find the selling price of 1 article. It would be $18/21 =$0.857.

Step 4: We know that the cost price of 1 article is $1 and the selling price of 1 article is$0.857. Therefore, the loss on 1 article is $1 -$0.857 = $0.143.

Step 5: To find the loss percent, we use the formula (Loss/Cost Price) * 100. Substituting the values, we get ($0.143/$1) * 100 = 14.3%.

So, the loss percent is 14.3%.