Answer:
22 1/2 hours
Explanation:
There are several ways you can get there. One way is to use table values to form a sum of 60:
cars = 32×2 - 8×(1/2) = 64 -4 = 60
Then the corresponding hours are ...
hours = 12×2 - 3×(1/2) = 24 -1.5 = 22.5
It will take 22.5 hours to wax 60 cars.
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Another way to get there is to use proportions:
hours/cars = 3/8 = ??/60
Multiply by 60 to find ??
(60)(3/8) = ?? = 180/8 = 22.5 . . . . hours
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We can do these things because we have determined the relationship between hours and cars is proportional: 8/3 = 16/6 = 32/12. If it weren't proportional, some other strategy would be needed to answer the question.