The answer is D.
If x = number of boxes sold and y = price of nails box, then it is best represented by the equation y = 62 - x.
Checking:
If y = 20 and x = 42,
20 = 62 - 42
20 = 20
If y = 10 and x = 52.
10 = 62 - 52
10 = 10
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