Final answer:
After calculating the remaining square footage of sheet metal (2.7 ft²), the cost per square foot is found by dividing the remaining value of the sheet metal ($48.60) by the remaining square footage, which equals $18.00 per square foot.
Step-by-step explanation:
To find the cost per square foot of the sheet metal, you need to first determine how much sheet metal is left after the contractor has used some of it. The contractor started with 6.4 ft² of sheet metal and has used 3.7 ft², so they have 6.4 ft² - 3.7 ft² = 2.7 ft² left. The value of this remaining sheet metal is $48.60.
Next, to find the cost per square foot, divide the total value of the remaining sheet metal by the number of square feet remaining:
Cost per square foot = Total value of remaining sheet metal / Remaining square footage
Cost per square foot = $48.60 / 2.7 ft²
Cost per square foot = $18.00
Therefore, the cost per square foot of the sheet metal is $18.00.