Skill: Calculate unit rates

A unit rate tells how much of one quantity corresponds to exactly $1$ unit of another quantity. To find it, divide the amount by the number of units, and keep the units in the answer.

Example: A car travels $(84)$ miles using $(3.5)$ gallons of gas. What is the car’s rate in miles per gallon?

1. Identify the quantities:

   • Distance: $(84)$ miles
   • Gas: $(3.5)$ gallons

2. Since we want miles per gallon, divide miles by gallons:

$$\frac{84\text{ miles}}{3.5\text{ gallons}}$$

3. Calculate:

$$84 \div 3.5 = 24$$

4. Include the units:

$$\boxed{24\text{ miles per gallon}}$$

The car travels $(24)$ miles for every $1$ gallon of gas. The order matters: dividing gallons by miles would give gallons per mile, which is a different rate.