Answer:
$465 is the answer.
Explanation:
The equation is given as :

Where h is the number of hours worked and f is the number of fixtures installed.
We have been asked how much does Ben frank charge when he works 7 hours and installs 9 fixtures?
So, we will put the values of h 7 and f = 9 in the equation.

=

= $465
Therefore, Ben charges $465.