Answer: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.
