Question

A phone company charges for service according to the formula:C=30+0.04n, where n is the number of minutes talked, and C is the monthly charge, in dollars.

Answer 1

The equation is given below as

`\begin{gathered} C=30+0.04n \\ C=0.04n+30 \end{gathered}`

The general equation of a line is given below as

`\begin{gathered} y=mx+b \\ m=\text{slope} \\ b=\text{vertical intercept} \end{gathered}`

The graph represents the equation of cost in dollars against minutes

By comparing the coefficient, we will have the slope of the equation to be

`\frac{\text{change in C}}{\text{Change in n}}=(dC)/(dn)=0.04`

Hence,

The slope of the equation is = 0.04

The slope's units is dollars per minute

The vertical intercept of the equation is the point when the value of n=0

`\begin{gathered} C=30+0.04n \\ C=30+0.04(0) \\ C=30 \end{gathered}`

Hence,

The vertical intercept in this equation = 30