Answer
a. $R=7(x)+50$
b. 190 dollars
c. $P=5.5(x)-180$
d. 40 dollars
e. 33 windows
Work Step by Step
a. R=revenue, x=number of windows cleaned
$R=7(x)+50$
b. x=20
$R=7(20)+50$
$R=140+50$
$R=190$
c. $P=(7-1.50)x+(50-230)$
$P=5.5(x)-180$
d. x=40
$P=5.5(40)-180$
$P=220-180$
$P=40$
e. P=0
$0=5.5(x)-180$
$0+180=5.5(x)$
$180=5.5(x)$
$180\div5.5=x$
$x=32.72$
$x=33$