Proportion Solver — Formula
## How to Solve a Proportion
### Setup
**a/b = c/x**
### Cross-Multiplication
**a × x = b × c**
**x = (b × c) / a**
### Verification
After solving, check that a/b equals c/x.
### Setup
**a/b = c/x**
### Cross-Multiplication
**a × x = b × c**
**x = (b × c) / a**
### Verification
After solving, check that a/b equals c/x.
Exemplo Resolvido
If 3/4 = 9/x, find x.
- 3/4 = 9/x
- Cross multiply: 3x = 4 × 9 = 36
- x = 36/3 = 12
- Check: 3/4 = 0.75, 9/12 = 0.75