Applications of Ratio and Proportion

Mathematics — First Preparatory

Percentages and discounts

A percentage is a ratio with denominator 100.
For example, 25% means 25/100, which equals 1/4.
To find a percentage of a number, multiply the number by the percentage and divide by 100.
To find what percentage one quantity is of another, divide the first quantity by the whole and multiply by 100.
For a discount discount amount = original price × discount percentage ÷ 100, and price after discount = original price − discount amount.

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