Rod is paid $85 to install a screen door and $115 to install a wooden door. In one week he installed 18 doors and was paid a total of $1860. How many screen doors did Rod install?

Rod installed  7 screen doors

Step-by-step explanation:

Step 1

Let the number of screen door = x

And the number of wooden doors = y

since he installed 18 doors , we have that

screen door + wooden doors = 18

x + y = 18 equation 1

Also the cost to install a screen  door -= $85

and to install a wooden door = $115

And he was therefore paid a total of $1850

Therefore

85x + 115 y = $1860 equation 2

Step 2 Solving

x + y = 18 equation 1

85x + 115 y = $1860 equation 2

Multiplying equation 1 BY 85

85x + 85y= 1530 equation 3

85x + 115 y = $1860 equation 4

subtracting from equation 1 from (2)

115y- 85y= 1860-1530

30y=330

y = 330/30 = 11

To find x

x+ y=18

x= 18-y

x= 18-11= 7

Rod installed  7 screen doors and 11 wooden doors.