Question

A phone company offers two monthly plans. Plan A costs $ 20 plus an additional $0.12 for each minute of calls. Plan B costs $13 plus an additional $0.17 A) For what amount of calling do the two plans cost the same?B) What is the cost when the two plans cost the same?

Answer 1

Let:

• y, be the cost of the plan

,

• x, be the minutes spend on call

This way, we'll have:

Plan A:

$y=0.12x+20$

Plan B:

$y=0.17x+13$

If the two plans cost the same, we'll have that:

$0.12x+20=0.17x+13$

Solving for x :

$\begin{gathered} 20-13=0.17x-0.12x \\ \rightarrow7=0.05x \\ \rightarrow\frac{7}{0.05}=x \\ \\ \Rightarrow x=140 \end{gathered}$

A) The two plans will cost the same for 140 minutes on call

The cost will be:

$\begin{gathered} y=0.12(140)+20 \\ \Rightarrow y=36.8 \end{gathered}$

B) $36.80