Skill: Calculate unit rates

A unit rate tells how much of one quantity corresponds to exactly 1 unit of another quantity.

To find a unit rate:

1. Identify the two quantities and their units.
2. Divide the first quantity by the second quantity.
3. Write the answer with units.
4. Check that the denominator is $1$.

Example: A car travels $156$ miles in $3$ hours. What is its speed in miles per hour?

Write the rate as a fraction:

$$\frac{156\text{ miles}}{3\text{ hours}}$$

Divide both quantities by $3$:

$$\frac{156\text{ miles}}{3\text{ hours}}=\frac{52\text{ miles}}{1\text{ hour}}$$

So, the unit rate is:

$$\boxed{52\text{ miles per hour}}$$

This means the car travels $52$ miles in $1$ hour. Be careful about the order: dividing hours by miles would give a different rate, such as hours per mile.