Equivalent ratios are the same comparison. Multiply both numbers by the same number to make one. 3 : 4 times 2 is 6 : 8. Adding the same number to both (5 : 6) breaks the ratio.
Worked example
The ratio of cups of juice to cups of soda is 4 : 3. How many cups of soda go with 16 cups of juice?
Answer:12 cups of soda
The ratio 4 : 3 is already in lowest terms. 16 is 4 × 4, so multiply the other number by 4 too: 3 × 4 = 12.
For grown-ups: Ratio tables, tape diagrams, double number lines; plot ratio pairs. Below: three problems to try with the worked answers, and a free printable sheet. Children can practise the same skill as a game, with no sign-up and no ads.
CCSS 6.RP.A.3a
What this practises, for teachers
Practices ratio tables, tape diagrams, double number lines; plot ratio pairs (6.RP.A.3a). A printable sheet with its answer key, worked answers on the page, no accounts.