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.

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) (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,

So then when ,

.
.
$0.90.

RELATED QUESTIONS
A 15 minute long-distance phone call costs $.90. The cost varies directly as the length... (answered by advanced_Learner)

a long distance phone call cost $1.75 plus $0.30 for each minute of the call. Write and... (answered by VFBundy)

the cost of a long-distance phone call is $0.41 for the first minute and $0.32 for each... (answered by ikleyn,MathTherapy)

A long-distance company charges $2.25 for a 6-minute call. An 12-minute call costs $3.75 (answered by greenestamps)

the cost of a long distance telephone call is $.95 for the first minute and $.08 for each (answered by rfer)

The cost of a long distance telephone call is determined by a flat fee for the first 5... (answered by ankor@dixie-net.com)

A 4-min call cost $2.65 and a 10-min call cost 4.75. What is the linear equation (answered by MathLover1)

When making a telephone call using a calling card, a call lasting 6 minutes cost $1.65. A (answered by jorel1380)

Solve. When making a telephone call using a calling card, a call lasting 5 minutes... (answered by ewatrrr)