When dealing with multiple items in a transaction, understanding the overall profit or loss requires careful consideration of the costs and revenues associated with each item. This module will guide you through the principles and calculations involved in such scenarios, crucial for competitive exams like the CAT.

The fundamental concepts of Cost Price (CP), Selling Price (SP), Profit, and Loss remain the same. However, when multiple items are involved, we often aggregate these values to determine the overall financial outcome of the entire transaction.

To find the overall profit or loss in a transaction involving multiple items, you need to sum up the total cost price of all items and the total selling price of all items. The difference between these two totals will reveal the overall profit or loss.

A common scenario involves selling two items at the same selling price. If one item is sold at a profit of 'x%' and the other at a loss of 'x%', there is always an overall loss. The formula for this specific case is: Overall Loss % = (x/10)^2 %.

When two items are bought at the same cost price, and one is sold at a profit of 'x%' and the other at a loss of 'y%', the overall profit or loss percentage can be calculated by finding the total SP and total CP.

When tackling problems with multiple items, always focus on calculating the total cost price and total selling price. Be wary of shortcuts that only apply to specific conditions, such as equal selling prices. Practice a variety of problems to build confidence and speed.