The amount of money that Sarah earns varies directly with the number of hours worked. If Sarah earns $320 for working 40 hours, determine the constant of proportionality.(1 point)
To determine the constant of proportionality, we can set up a proportion:
$\frac{\text{Amount of money earned}}{\text{Number of hours worked}} = \text{Constant of proportionality}$
We are given that Sarah earns $320 for working 40 hours. Plugging these values into the proportion:
$\frac{320}{40} = \text{Constant of proportionality}$
Simplifying the fraction:
$8 = \text{Constant of proportionality}$
Thus, the constant of proportionality is $\boxed{8}$.