I need help with both questions.

Answer:
y = 17x
$595
Step-by-step explanation:
[tex]\frac{y_{2} -y_{1} }{x_{2} -x_{1} }[/tex] = [tex]\frac{85 - 51}{5 - 3}[/tex] = [tex]\frac{34}{2}[/tex] = 17 (find the slope, gradient or rate of change)
The y intercept is 0. Zero hours = 0 charge.
y = 17(35)
y = 595