Comparing Quantities - Profit and Loss as a Percentage

Cost Price (CP) and Selling Price (SP): The Cost Price is the amount paid to purchase an item, including any additional expenses like carriage or repairs. The Selling Price is the amount at which the item is sold to a customer. Visually, think of CP as the 'investment' and SP as the 'return' on a timeline of a transaction.

Profit: When the Selling Price ($SP$) is greater than the Cost Price ($CP$), the difference is called profit. Imagine a bar graph where the $SP$ bar is taller than the $CP$ bar; the extra portion on top of the $SP$ bar represents the profit earned.

Loss: When the Cost Price ($CP$) is greater than the Selling Price ($SP$), the difference is called loss. In a visual representation, the $CP$ bar would be taller than the $SP$ bar, and the 'missing' height in the $SP$ bar compared to the $CP$ bar illustrates the loss incurred.

Profit and Loss Percentage: Profit or loss is often expressed as a percentage of the Cost Price. It is crucial to remember that the $CP$ always acts as the base (the denominator) for calculating these percentages. Think of a pie chart where the $CP$ represents the whole ($100\%$), and the profit or loss is a slice measured relative to that whole.

Effective Cost Price (Overhead Expenses): Sometimes, additional costs like transportation, labor, or repairs are spent after buying an item. These are called overheads and are added to the original purchase price to find the 'Effective Cost Price'. Visually, this is like a stack of blocks where the base is the purchase price and the smaller blocks on top are the overheads, forming one total $CP$ pillar.

Break-even Point: If the Selling Price is exactly equal to the Cost Price ($SP = CP$), there is neither profit nor loss. On a scale, this would look like two perfectly balanced weights of equal size on both sides.