VCE · Topic explainer

Fractions of amounts in Foundation Maths

A fraction tells you how many equal parts of a whole you have. To find a fraction of an amount, divide by the denominator, then multiply by the numerator. When a ratio describes two ingredients in a mixture, add the ratio parts first. The total number of parts becomes the denominator for each ingredient’s share.

Worked example

A gardener mixes two liquids in the ratio 3:5 to make 32 L. The whole batch represents 3 + 5 = 8 equal parts. One part is 32 ÷ 8 = 4 L.

The first liquid is 3/8 of 32 L, or 12 L. The second is 5/8, or 20 L. Check that the amounts add to 32 L and that 12:20 simplifies to 3:5.