Question

Alexandra paid $7 to park her car for 3 hours at the parking garage. The garage charges a constant hourly parking rate. Write an equation that shows the relationship between p, the number of hours parked, and c, the cost in dollars.

Answer 1

c=7/3p

Explanation:

Answer 2

Let's first find the hourly parking rate:

`\frac{\$ 7}{3 \,\textrm{hours}} = \frac{p}{1 \,\textrm{hour}}`

• Set up

`\$ 7 \cdot 1\,\textrm{hour} = p \cdot 3 \,\textrm{hours}`

• Cross multiply over the = sign

`\$ 7 = 3p`

• Divide both sides by
  `1 \,\textrm{hour}`

`p = (\$ 7)/(3) = \$ (7)/(3)`

• Divide both sides by 3

The hourly rate is
`\$ (7)/(3)`, so now let's make that into an equation.

`c = \$ (7)/(3) p`

• This equation says that the cost is equivalent to the rate of
  `\$ (7)/(3)` multiplied by the number of hours parked

The equation is
`\boxed{c = \$ (7)/(3) p}`.