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When making a telephone call using a calling card, a call lasting 5 minutes cost $0.95. A call lasting 13 minutes cost $1.75. Let y be the cost of making a call lasting x minutes using a calling card. Write a linear equation that models the cost of making a call lasting x minutes.

A. y = 10x - 981/20
B. y = -0.1x + 1.45
C. y = 0.1x + 0.45

Respuesta :

calculista

Answer:

We are basically searching for the equation of the line

(y-yo) = m*(x - xo)

Where,

m is the slope of the line

(xo, yo) is an arbitrary point that belongs to the line

The slope can be found with the points given in the problem

(x1,y1) = (5 min , $0.95)

(x2,y2) =  (13 min , $1.75)

m = (y2 - y1) / (x2 - x1)

m = ($1.75 - $0.95) / (13 min  - 5 min)

m = 0.8/ 8 = 0.1 $/min

(y-0.95) = 0.1*(x - 5)

y = 0.1*x + 0.45

Option C

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