Answer:
The cost of a sheet metal per square foot is $30
Step-by-step explanation:
Given
Size of Sheet Metal = 8.2ft squared
Used Sheet Metal = 3.5ft squared
Worth of leftover sheet = $141
Equation: 
Required
Find the cost per square foot of the sheet metal
Solving for x in the above equation will give the cost per square foot of the sheet metal.


Divide both sides by 4.7



Hence, the cost of a sheet metal per square foot is $30