Let, the number of four door sedans = x
And the number of two door coupes = y
Given a total of 23 autos had window film applied.
So we can write the equation as,
.....equation 1
The charge of auto film for a four door sedan = $189.99.
Now the charge of auto film for x four door sedans = $
= $

Also given, the charge of auto film for a two door coupe = $159.99.
So, the charge of auto film for y two doos coupes = $
= $

The total receipts for the week = $4189.77
So we can write the equation as,
.....equation 2
From equation 1, we can write,

Now by substituting this value of x in equation 2 we will get,

By distributing 189.99 we will get,


To get y first we move 30y to the right side by adding it to both sides. We will get,


Now to get y , we will move 4189.77 to the left side by subtracting it from both sides. We will get,


Now to get , we will move 30 to the left side by dividing it to both sides. We will get,




So we have got the number of two door coupes = 6
The number of four door sedans =
.
We have got the required answer here.