a)
he charges a fixed cost of $12, meaning a one-time charge of 12 bucks, plus 1.50 for each window.
1 window................ 12 + 1.5(1)
2 windows............. 12 + 1.5(2)
3 windows............. 12 + 1.5(3)
4 windows............. 12 + 1.5(4)
x windows............. 12 + 1.5(x)

b)

Answer:
Sigh no body wants to answer this one, so I'll just take my points back
Hello :
cscx = -5/2
1/sinx =-5/2
sinx=-2/5
sin²x+cos²x=1
4/25+cos²x=25/25
cos²x = 21/25
between 270 and 360 : cosx > 0 cosx=(<span>√21)/5
but : sin2x =2sinx cosx
sin2x = 2(-2/5)(</span>(√21)/5)
sin2x = (-4√21)/25
6/7 divided by 3
6/7 times 1/3
6/21
3/7