Consider the question. Mr. Caiden wants to do repairs to his house and requires 300 feet of metal roofing to do this. If each foot of roofing costs $8, and the supplier of the metal roofing brings in 250 feet of metal roofing for free, how much money is Mr. Caiden required to pay for the remaining metal roofing?
 If the answer is '400'; explain the reasoning:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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The supplier brought 300 ft - 250 ft = 50 fewer feet of metal roofing. Therefore the total amount of money Mr. Caiden has to pay for the remaining metal roofings is 50 feet * $8 / foot = $400.