Skill: Use unit rates to solve problems

A unit rate tells how much of one quantity corresponds to exactly 1 unit of another quantity. Find it by dividing, and keep the units with your answer.

Example:
Six apples cost 4.50$. How much would 10 apples cost at the same rate?

1. Find the cost for 1 apple.

   Divide the total cost by the number of apples:

$$\$4.50 \div 6 = \$0.75$$

The unit rate is 0.75\text{ per apple}}$.

2. Use the unit rate to find the cost of 10 apples.

$$10\text{ apples} \times \$0.75\text{ per apple} = \$7.50$$

3. Answer the question.

$$\boxed{\text{10 apples cost }\$7.50.}$$

The 0.75$ is the cost for one apple, not the total cost. Multiplying it by the number of apples gives the total.