Respuesta :
Let, the number of regular driveways be x.
Given there are 3 fewer large driveways than regular driveways.
So, the number of large driveways = [tex] (x-3)[/tex]
Given, Carlas charges $10 for each regular driveway.
So for x regular driveway the amount will be = $ [tex] (10)(x)[/tex] = $ [tex] (10x)[/tex]
And he charges extra $7.50 for each large driveway.
So for each large driveway Carlos charges = $[tex] (10+7.50)[/tex] = $17.50.
For (x-3) large driveways Carlos will charge = $ [tex] (17.50)(x-3)[/tex] = $ [tex] (17.50x - 52.50)[/tex]
Given, the total amount he makes = $140
So we can write the equation as,
[tex] 10x + 17.50x - 52.50 = 140[/tex]
[tex] 27.50x + 52.50 = 140[/tex]
We will move 52.50 to the right side by adding it to both sides. We will get,
[tex] 27.50x - 52.50 + 52.50 = 140 + 52.50[/tex]
[tex] 27.50x = 192.50 [/tex]
Now to get x, we will move 27.50 to the right side by dividing it to both sides. We will get,
[tex] \frac{(27.50x)}{27.50} =\frac{192.50}{27.50}[/tex]
[tex] x =\frac{192.50}{52.50}[/tex]
[tex] x = 7[/tex]
So we have got the required answer.
The number of regular driveways Carlos shovel = 7.