How to Solve Proportions with Cross Multiplication
The fundamental property of equal ratios:
STEP 01
Set Up Ratio
Write proportion in equation form: a / b = c / x.
STEP 02
Cross Multiply
Multiply diagonally across: a · x = b · c.
STEP 03
Isolate x
Divide both sides by a to isolate unknown: x = (b · c) / a.
STEP 04
Check Equality
Verify that both simplified ratios equal the exact same decimal proportion.