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.

Write an equation in the standard form to represent the total rent (y) that Sam has to pay for renting the boat for x days. (4 points)

Part B: Write the equation obtained in Part A using function notation.(2 points)

Part C: Describe the steps to graph the equation obtained above on the coordinate axes. Mention the labels on the axes and the intervals. (4 points)

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.