7. charlotte has a babysitting service and charges $12.50 per hour.
after charlotte calculated her set-up and travel costs, she constructed
the cost equation c = 45 + 2.50h, where c represents
the cost in dollars per job and h represents the hours
charlotte babysits for.
a. write an equation that represents the revenue, r, earned by
charlotte in terms of number of hours, h.
b. by solving the equations simultaneously, determine the number of hours charlotte needs to babysit
to cover her costs (that is, the break-even point).
c. in one week, charlotte had four babysitting jobs as shown in the table.
babysitting job
number of hours (h) 5.0 3.5 4.0
7.0
i. determine whether charlotte made a profit or loss for each individual babysitting job.
ii. did charlotte make a profit this week? justify your answer using calculations.
d. charlotte made a $50 profit on one job. determine the total number of hours she babysat for.

Step-by-step explanation:

Charlotte's revenue earned : R = 12.50hwhere R = revenue earned and h represents hrs worked

break even point :

12.50h = 45 + 2.50h

12.50h - 2.50h = 45

10h = 45

h = 45/10

h = 4.5 <== she would have to work 4.5 hrs to break even

revenue - expenses = profit / loss

for 5 hrs...h = 5                                        for 3.5 hrs

12.50(5) - (45 + 2.5(5)) =                    12.50(3.5) - (45 + 2.5(3.5)) =

62.5 - (45 + 12.5) =                             43.75 - (45 + 8.75) =

62.5 - 57.5 = $ 5 profit                       43.75 - 53.75 = -10$ 10 loss

for 4 hrs                                                for 7 hrs

12.50(4) - (45 + 2.50(4)) =                    12.50(7) - (45 + 2.50(7)) =

50 - (45 + 10) =                                     87.5 - (45 + 17.5) =

50 - 55 = - 5$ 5 loss                        87.5 - 62.5 = $ 25 profit

12.50h - (45 + 2.50h) = 50

12.50h - 45 - 2.50h = 50

10h - 45 = 50

10h = 50 + 45

10h = 95

h = 95/10

h = 9.5 <=== she would have to work 9.5 hrs to make a $ 50 profit

final answer is : )

1/4 because there is 4 grades.