20 points
2 answers:
Answer: 
which is choice C
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Explanation:
x = total number of minutes spent using the vacuum
If x is larger than 15, then x-15 represents the amount of time spent past the first 15 minutes. The machine will charge 15 cents per minute at this point. The machine will charge 0.15 dollars for (x-15) minutes. So 0.15*(x-15) dollars is charged on top of the $2 already spent for those first 15 minutes.
In total, the cost for Caroline is
T = 2+0.15(x-15)
This total must not be larger than $7. The total T can be equal to 7 or smaller than 7
So,
============================================================
Explanation:
x = total number of minutes spent using the vacuum
If x is larger than 15, then x-15 represents the amount of time spent past the first 15 minutes. The machine will charge 15 cents per minute at this point. The machine will charge 0.15 dollars for (x-15) minutes. So 0.15*(x-15) dollars is charged on top of the $2 already spent for those first 15 minutes.
In total, the cost for Caroline is
T = 2+0.15(x-15)
This total must not be larger than $7. The total T can be equal to 7 or smaller than 7
So,
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