SOLUTION: The post office charges a flat rate plus a per pound rate to send packages. For a three pound package it costs $6.50 and for a 7 pound package it costs $12.50. A. What is the eq

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: The post office charges a flat rate plus a per pound rate to send packages. For a three pound package it costs $6.50 and for a 7 pound package it costs $12.50. A. What is the eq      Log On


   

Question 1113193: The post office charges a flat rate plus a per pound rate to send packages. For a three pound package it costs $6.50 and for a 7 pound package it costs $12.50.
A. What is the equation for the cost of package based on its weight
B. What is the slope and what does it represent
C. What is the y-intercept and what does it represent
I tried to find the unit rate but could not because I feel like I am missing information?
Answer by josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!
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For a three pound package it costs $6.50 and for a 7 pound package it costs $12.50.
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x, size in weight
y, cost of package

Points (x,y):
(3, 6.5) and (7, 12.5).

m=%2812.5-6.5%29%2F%287-3%29
m=6%2F4=3%2F2

y=mx%2Bb
y-mx=b
b=y-mx

b=6.5-%283%2F2%29%2A3
b=6.5-9%2F2
b=6.5-4.5
b=2

highlight%28y=%283%2F2%29x%2B2%29
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A rate per pound of $1.5 and a fixed fee of $2 for any size package