Question 1016777: The phone company NextFell has a monthly cellular plan where a customer pays a flat monthly fee and then a certain amount of money per minute used on the phone. If a customer uses 360 minutes, the monthly cost will be $215. If the customer uses 800 minutes, the monthly cost will be $435.
Find an equation in the form y = m x + b, where x is the number of monthly minutes used and y is the total monthly of the NextFell plan.
Answer by macston(5194)   (Show Source):
You can put this solution on YOUR website! .
y=total cost; b=flat fee, m=cost per minute; x=number of minutes
.
y=b+mx
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For x=360 minutes:
$215=b+360m
$215-360m=b
.
For x=800 minutes:
$435=b+800m
$435-800m=b
.
$435-800m=$215-360m
$220=440m
$0.50=m
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Cost per minute m=$0.50
.
For x=360:
b=$215-360m
b=$215-360($0.50)
b=$215-$180=$35
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The flat fee b=$35
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ANSWER: Equation is y=$0.50x+$35
.
CHECK: Use x=$800; y=$435
.
y=$0.50x+$35
$435=$0.50(800)+$35
$435=$400+$35
$435=$435
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