SOLUTION: A 4-min call cost $2.65 and a 10-min call cost 4.75. What is the linear equation

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Question 934348: A 4-min call cost $2.65 and a 10-min call cost 4.75. What is the linear equation

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
given:
A 4-min call cost $2.65 and a 10-min call cost 4.75.
the linear equation: y=mx%2Bb where x a number of minutes and y a cost, m a slope or in your case cost of a 1-mincall and b is y-intercept or in your case any additional fixed cost
if x=4 and y=2.65, then we have
2.65=4m%2Bb.............eq.1
if x=10 and y=4.75, then we have
4.75=10m%2Bb.............eq.2
sole this system to find m and b
2.65=4m%2Bb.............eq.1
4.75=10m%2Bb.............eq.2
______________________________..subtract eq.1 from eq.2
4.75-2.65=10m%2Bb-4m-b
2.1=6m
2.1%2F6=m
highlight%28m=0.35%29
go to 2.65=4m%2Bb......eq.1 substitute 0.35 for m and find b
2.65=4%2A0.35%2Bb
2.65=1.4%2Bb
2.65-1.4=b
highlight%28b=1.25%29
so, your equation is:y=0.35x%2B1.25