Answer:
The costs of the plan are $0.15 per minute and a monthly fee of $39
Step-by-step explanation:
Let
x ----> the number of minutes used
y ----> is the total cost
step 1
Find the slope of the linear equation
The formula to calculate the slope between two points is equal to
[tex]m=\frac{y2-y1}{x2-x1}[/tex]
we have the ordered pairs
(100,54) and (660, 138)
substitute
[tex]m=\frac{138-54}{660-100}[/tex]
[tex]m=\frac{84}{560}=\$0.15\ per\ minute[/tex]
step 2
Find the equation of the line in point slope form
[tex]y-y1=m(x-x1)[/tex]
we have
[tex]m=0.15\\point\ (100,54)[/tex]
substitute
[tex]y-54=0.15(x-100)[/tex]
step 3
Convert to slope intercept form
Isolate the variable y
[tex]y-54=0.15x-15\\y=0.15x-15+54\\y=0.15x+39[/tex]
therefore
The costs of the plan are $0.15 per minute and a monthly fee of $39
