Question

Word problem: When making a phone call using calling card a call lasting 3 minutes costs $1.60. A call lasting 10 minutes costs $4.40. Let y be the cost of making a call lasting x minutes using a calling card. Write a linear equation that relates to the cost of making the call y, to the time x.

Answer 1

You are given two points:

"a call lasting 3 minutes costs $1.60"
the time, x, is 3 min; the cost, y, is $1.60
(3, 1.60)

"a call lasting 10 minutes costs $4.40"
What do you think the point is from here?

After finding the two points, find the linear equation like you would for any other two points.

Answer 2

40