Answer :
A.
y=mx+b
m=slope or price per unit of x
b=initial value or y intercept or fixed value
so
company A is 6 dollar per unit of window and a fixed value of 12 so
A=6x+12 when A=amount you need to pay and x=number of windows washed
company B is 5 dollar per unit of window and a fixed value of 15 so
B=5y+15 where B=amount you need to pay and y=number of windows
B.
8 windows
A=6(8)+12=48+12=60
B=5(8)+15=40+15=55
60>55
company B would cost less because 55<60
C. 6 windows
A=6(6)+12=36+12=48
B=5(6)+15=30+15=45
48-45=3
$3 are saved
y=mx+b
m=slope or price per unit of x
b=initial value or y intercept or fixed value
so
company A is 6 dollar per unit of window and a fixed value of 12 so
A=6x+12 when A=amount you need to pay and x=number of windows washed
company B is 5 dollar per unit of window and a fixed value of 15 so
B=5y+15 where B=amount you need to pay and y=number of windows
B.
8 windows
A=6(8)+12=48+12=60
B=5(8)+15=40+15=55
60>55
company B would cost less because 55<60
C. 6 windows
A=6(6)+12=36+12=48
B=5(6)+15=30+15=45
48-45=3
$3 are saved