SOLUTION: Suppose the cost of a long distance call is related to the duration of the call by linear equation, the cost of a 20 minute call is $.70 and the cost of a 35 minute call is $1.00.

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Suppose the cost of a long distance call is related to the duration of the call by linear equation, the cost of a 20 minute call is $.70 and the cost of a 35 minute call is $1.00.       Log On


   

Question 945209: Suppose the cost of a long distance call is related to the duration of the call by linear equation, the cost of a 20 minute call is $.70 and the cost of a 35 minute call is $1.00. Find the cost of a 30 minute call.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Use the two points to find the equation of the cost line.
First find the slope.

Then use the point-slope form of a line with either point,
y-1=0.02%28x-35%29
y-1=0.02x-0.70
y=0.02x%2B0.30
So then when x=30,
y=0.02%2830%29%2B0.3
y=0.6%2B0.3
highlight%28y=0.9%29%29
.
.
$0.90.