A ratio compares quantities, e.g. $8:12$, which simplifies to $2:3$ (divide both by 4).
A rate compares two different units — like speed in km/h. In proportion, two ratios are equal. Example: if $3:5 = 9:?$, the missing value is $15$ (both parts multiplied by 3).
Remember
- Simplify a ratio by dividing both parts by the same number.
- Proportion keeps ratios equal.