Given that the monthly cost (in dollars) of a long-distance phone plan is a linear function of the total calling time (in minutes) then this can be presented in a table form as;
<u>Time in minutes (x)</u> <u>Cost in dollars (y)</u>
50 $12.55
102 $ 17.23
Take the values as ordered pairs to represent coordinates for points that satisfy the linear function
(50,12.55) and (102,17.23)
Finding the slope of the graph using these points
slope,m=Δy/Δx
m=Δy=17.23-12.55 =4.68
Δx=102-50=52
m=4.68/52 =0.09
Finding the equation of the linear function using m=0.09, and point (50,12.55)
