Question

PART A: Maria rented a coat at $285 for 3 days. If she rents the same coat for 60 days, she has to pay a total rent of $510. Write an equation in standard form to represent the total rent (y) that Maria has to pay for renting the coat for x days.
PART B: Write the equation obtained in Part A using function notation.
PART C: Describe the steps to graph the equation obtained above on the coordinate axes. Mention the labels on the axes and the intervals.

Answer 1

1) Name the variables

Number of days: x

rent: y

2) state the initial points

   x           y
days        $

  3           285

60           510


3) assume linear relation:

=> (y - yo) / (x - xo) = (y1 - yo) / (x1 - xo)

=> (y - 285) / (x - 3) = (510 - 285) / (60 - 3)

=> (y - 285) / (x - 3) = 225 / 57 = 75 / 19

=> 19 (y - 285) = 75 (x - 3)

=> 19y - 19*285 = 75x - 75*3

=> 19y - 75x = 5415 - 225

=> 19y  - 75x = 5190

=> standar form = -75x + 19y = 5190


PART B: Write the equation obtained in Part A using function notation.

-75x + 19y = 5190

=> 19y = 5190 + 75x

=> y = 5190/19 + (75/19)x

=> function notation = f(x) = (75/19)x + 5190 / 19

PART C: Describe the steps to graph the equation obtained above on the coordinate axes. Mention the labels on the axes and the intervals.

1) Coordinate axes:

x: number of days

y: rent

2) draw the two given points: (3,285) and (60, 510)

3) draw the line that joins those points from the interception of the y-axis until some points further (60, 510).