Question

Part A: Sam rented a boat at $225 for 2 days. If he rents the same boat for 5 days, he has to pay a total rent of $480.

Answer 1

Part A
Let y = a  + b*x
where
x = number of days
y = cost

When x = 2, y =$225. Therefore
a + 2b = 225                  (1)
When x = 5, y = 480. Therefore
a + 5b = 480                 (2)
Subtract (1) from (2).
3b = 480-225 = 255
b = 85
From (1), obtain
a = 225 - 2*85 = 55

Answer: 
y = 55 + 85x
where x =  the number of days
y = the cost (dollars)

Part B.
The cost is
f(x) = 55 + 85x

Part C
To graph y = 55 + 85x,
The y-intercept is 55
The x-intercept occurs when y = 0. That is
55 + 85x = 0
x = -55/85 = -11/17
The graph is shown below.