SOLUTION: A carpet cleaning service charges $90 for a five-hr job and $126 for an eight-hr job. What would they charge for a 10-hr job?

Question 278885: A carpet cleaning service charges $90 for a five-hr job and $126 for an eight-hr job. What would they charge for a 10-hr job?
Answer by checkley77(12844) (Show Source): You can put this solution on YOUR website!
90/5=18 dollars per hour.
126/8=15.75 dollars per hour.
(5,18) & (8,15.75) are 2 points on the line projection.
Slope=(15.75-18)/(8-5)
Slope=-2.25/3=-.75
18=5*-.75+b
18=-3.75+b
b=18+3.75
b=21.75
y=-.75x+21.75
y=-.75*10+21.75
y=-7.5+21.75
y=14.25 dollars per hour for a 10 hour job.

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