When this tool helps
A ratio problem is only clear when you know which value goes in each position. This tool solves the specific equation A / B = C / X. It does not infer a different arrangement from a sentence or decide which quantities should be proportional.
Enter A, B and C in the labelled fields. Think about the paired quantities before entering them: A and C occupy matching numerator positions, while B and X occupy matching denominator positions. For a genuine direct proportion, both pairs should describe the same relationship.
What to enter
These are the candidate Android fields, not a form on this website. Editable fields in the app start empty; modes and units are selected separately.
- A · numerator of first ratio
- The top of the known ratio.
- B · denominator of first ratio
- The bottom of the known ratio.
- C · numerator of second ratio
- The known top of the second ratio; X is calculated beneath it.
Try this example after the update is available
The values below explain the calculation. They are not a quote, a live measurement or an automatic answer for your situation.
- A
- 6
- B
- 3
- C
- 10
Checked example result5
The first ratio is 6 / 3 = 2. The second must satisfy 10 / X = 2, so X is 5.
Formula and assumptions
A / B = C / X, therefore X = B × C ÷ A
- A, B and C must all be non-zero in this candidate’s supported equation. Negative non-zero inputs are allowed.
- The tool checks arithmetic, not whether a real-world relationship is actually proportional or whether units match.
A common mistake to avoid
Do not swap B and C simply because their order looks convenient. Write the complete equation first; the candidate solves only the layout displayed above.
Find this tool in the Android update
- When you have the redesigned Android update, open Tools and search for Proportion, or find it under Numbers.
- Open the tool, choose the mode or units relevant to your task, then enter your own values.
- Review the result and explanation. Use Calculate & save only if you want the calculation kept in local History; Copy result does not send it to our server.
This guide is an educational preview of the update in testing, not an announcement that Google Play has approved or published it. Calculations are in the native app; no web calculator or download is offered on this page.
Questions about Proportion
Can A, B or C be zero?
No. This candidate rejects zero for any of the three known positions instead of attempting ambiguous or undefined ratio cases.
Does this solve inverse proportions automatically?
No. It solves A / B = C / X exactly as labelled. You must choose an appropriate model for your problem.