Question

Elizabeth's cell phone plan lets her choose how many minutes are included each month. The table shows the plan's monthly cost y for a given number of included minutes X. Write an equation in slope- intercept form to represent the situation. 100 200 300 400 500 Minutes included, x Cost of plan ($), y 14 20 26 32 38

Answer 1

`y=(3x)/(50)+8`

Step-by-step explanation

Step 1

select two points from the table

Let

P1(100,14) and P2(200, 20)

Step 2

find the slope using

`\begin{gathered} \text{slope}=\frac{y_2-y_1}{x_2_{}-x_1}_{} \\ \text{where (x}_1,y_1)and(x_2,y_2\text{) are the coordinates of the knownpoitns} \end{gathered}`

replace,

`\begin{gathered} \text{slope}=(y_2-y_1)/(x_2-x_1)_{} \\ \text{slope}=(20-14)/(200-100)=(6)/(100)=(3)/(50)_{} \end{gathered}`

Step 3

use the slope-point equation, P1 and slope

`\begin{gathered} y-y_0=slope(x-x_0) \\ y-14=(3)/(50)(x-100) \\ y=(3x)/(50)-(300)/(50)+14 \\ y=(3x)/(50)-6+14 \\ y=(3x)/(50)+8 \\ \end{gathered}`