Answer: 
Step-by-step explanation:

X=9
You would do 54 divided by 5x and it would equal to 9 that means x is 9
To find the length of the room you will have to add up all of the sides and divide by four
Answer:
15 dollars
Step-by-step explanation:
12 inches = 1 ft
so 12 inch by 12 inches is 1 ft * 1 ft
1 ft* 1 ft
1 ft^2
This is smaller than 3 ft^2 so they will get charged for 3 ft^2
3 ft^2 = 3 ft^2 * $5 / ft^2 = 15 dollars