Profit is selling price minus cost price; loss is cost price minus selling price. A profit or loss percentage is normally based on cost price when the question says so. A discount percentage uses the marked price. Always identify the specified base. Example An item costs a retailer $80 and sells for $100. Profit is $20, so profit as a percentage of cost is 2080 x 100%=25%. As a percentage of selling price it is 20%; these answer different questions. For an illustrative restaurant bill of $60, suppose the question specifies 10% service charge and then 8% tax on the service-inclusive subtotal. The total is 60(1.10)(1.08)=$71.28. The supplied rates are example assumptions, not claims about current charges. Apply each charge to the base stated in the question; do not simply add successive percentage rates.

Profit is selling price minus cost price; loss is cost price minus selling price. A profit or loss percentage is normally based on cost price when the question says so. A discount percentage uses the marked price. Always identify the specified base.

An item costs a retailer $\$80$ and sells for $\$100$. Profit is $\$20$, so profit as a percentage of cost is $\dfrac{20}{80}\times100\%=25\%$. As a percentage of selling price it is $20\%$; these answer different questions.

For an illustrative restaurant bill of $\$60$, suppose the question specifies $10\%$ service charge and then $8\%$ tax on the service-inclusive subtotal. The total is $60(1.10)(1.08)=\$71.28$.

The supplied rates are example assumptions, not claims about current charges. Apply each charge to the base stated in the question; do not simply add successive percentage rates.

Profit, discounts and stated charges

Profit, discounts and stated charges