1) Ellen Murphy manages an Auto Film outlet that applies window films to automobile windows.

She reported that last week a total of 28 autos had

window film applied. Auto Film charges $129.99

for a four-door sedan and $99.99 for a two-door

coupe. If Ellen had total receipts for the week of

$3,459.72, how many four-doors sedans had been

serviced? How many two-door coupes?

Four-door sedan = 22

Two-door coupes = 6

Step-by-step explanation:

This is an algebra problem.

Let "x" represent number of four-door sedan,

"y" represent two-door coupe.

Since there are total of 28 autos on which film is applied, we have:

x + y = 28                                         Equation 1

y = 28 - x                                          Equation 2

Also provided,

Total revenue = $3,459.72

That means,

129.99x + 99.99y = 3,459.72          Equation 3

Putting value of "y" from Equation 2 in Equation 3 we have:

129.99x + 99.99(28 - x) = 3,459.72

129.99x + 2,799.72 - 99.99x = 3,459.72

30x = 660

x =

Therefore, number of four door sedans = 22

Further y that is two door sedan = 28 - x = 28 - 22 = 6

answer: the common difference is -0.10