AI generatedRatio, proportion and rates of changeKS3 / GCSE

Combining two linked ratios

Identify the quantity that appears in both ratios. Its number of parts must match.

  • Identify the quantity that appears in both ratios. Its number of parts must match.
  • Scale each whole ratio so that the shared quantity has the same number, using a common multiple.
  • Read off the three-part ratio in the requested order and simplify if possible.

Example 1

Combine and to find .

Multiply both parts by 2.Multiply both parts by 3.

Example 2

Combine and to find .

Multiply both parts by 3.Multiply both parts by 4.

Remember
Use the worked steps to check your method, not just the final answer.

Your turn

Question 1

Combine and to find .

Check answer
Multiply both parts by 4.Multiply both parts by 5.

B now represents the same number of parts in both ratios.

Question 2

Combine and to find .

Check answer
Multiply both parts by 5.Multiply both parts by 6.

B now represents the same number of parts in both ratios.

Question 3

Combine and to find .

Check answer
Multiply both parts by 6.Multiply both parts by 7.

B now represents the same number of parts in both ratios.

Question 4

Combine and to find .

Check answer
Multiply both parts by 1.Multiply both parts by 4.

B now represents the same number of parts in both ratios.

Question 5

Combine and to find .

Check answer
Multiply both parts by 1.Multiply both parts by 3.

B now represents the same number of parts in both ratios.

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