Find the percentage gain or loss when the dot pens bought for Rs. 96 per dozen were sold atthe rate of 10 for Rs. 90?

Step 1: First, we need to find the cost price of each pen. Since the pens were bought for Rs. 96 per dozen, and a dozen contains 12 items, the cost price of each pen is Rs. 96/12 = Rs. 8.

Step 2: Next, we need to find the selling price of each pen. Since 10 pens were sold for Rs. 90, the selling price of each pen is Rs. 90/10 = Rs. 9.

Step 3: Now, we can calculate the gain. The gain is the selling price minus the cost price, which is Rs. 9 - Rs. 8 = Rs. 1.

Step 4: Finally, we can calculate the percentage gain. The formula for percentage gain is (Gain/Cost price) * 100. Substituting the values we have, the percentage gain is (Rs. 1/Rs. 8) * 100 = 12.5%.

So, there is a 12.5% gain in selling the pens.