Answer:$108
Step-by-step explanation:
Given
Bedroom door is [tex]9\ ft[/tex] tall
width of the door is [tex]3\ ft[/tex]
Rate [tex]R=\$4/ m^2[/tex]
The area of the door is [tex]l\times w[/tex]
[tex]\Rightarrow A=9\times 3=27\ m^2[/tex]
Cost is given by
[tex]\Rightarrow C=27\times 4=\$108[/tex]