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)
[tex]\bf \stackrel{cost}{y}=\stackrel{\stackrel{fixed}{cost}}{12}+\stackrel{\stackrel{per}{window}}{1.5x}[/tex]
b)
[tex]\bf \stackrel{cost}{28.50}=\stackrel{\stackrel{fixed}{cost}}{12}+\stackrel{\stackrel{per}{window}}{1.5x}\implies 16.50=1.5x\implies \cfrac{16.50}{1.5}\implies \boxed{11=x}[/tex]
