SOLUTION: Mary is certain that every time she parks in the municipal garage it costs her at least $2.15 if the garage charges 35 cents plus 30 cents for each half hour, how long is Mary's ca

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Question 280428: Mary is certain that every time she parks in the municipal garage it costs her at least $2.15 if the garage charges 35 cents plus 30 cents for each half hour, how long is Mary's car parked? Mary's cost is at least $2.15 when Mary's car is parked at least ____ hours.
Found 2 solutions by richwmiller, stanbon:
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
This is not a coin problem!
this is a linear equation problem
y=.30x+.35
where x is each half hour parked
2.15=.30x+.35
1.80=.30x
180=30x
6=x
x= 6 half hours to be charged 2.15 for a total of three hours

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Mary is certain that every time she parks in the municipal garage it costs her at least $2.15 if the garage charges 35 cents plus 30 cents for each half hour, how long is Mary's car parked?
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Cost = 35 + 30(2x) where x is number of hours.
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Solve 35 + 30(2x) >= 215 cents
30(2x) >= 180
x >= 3 hrs
Mary's cost is at least $2.15 when Mary's car is parked at least 3 hours
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Cheers,
Stan H.