Let's assume
x is number of hours worked
y is amount paid
Since, this is linear relationship
We can select any two points
(2,36.50) and (4,73)
so, we can also write as
x1=2 , y1 =36.50
x2=4 , y2=73
Firstly, we can find slope

we can plug values


now, we can use point slope form of line

we can plug values

now, we can solve for y

or
..............Answer
The independent variable, x, represents the SIDE LENGTHS, and the dependent variable is the PERIMETER, because the PERIMETER, depends on the SIDE LENGTHS.
If it is what I think it is (-8 divided by 2/7), then the answer is -28.
You would have to factor using difference of cubes and set each factor equal to 0.