so if you use it for less than 5 minutes is more than likely free.
now, you start downloading the macarena song and other mp3s, and it takes longer then they charge 10 cents or $0.10 per minute after those 5 minutes.
so, if you use it
6 mins you pay 1 * 0.10
7 mins you pay 2 * 0.10
8 mins you pay 3 * 0.10
9 mins you pay 4 * 0.10
10 mins you pay 5 * 0.10
x mins you pay (x - 5) * 0.10 so long "x" is 5 or higher.
now, they charge a $5 fee, that's just a connection fee, so is charged only once,
so the cost function will be
[tex]\bf \stackrel{cost}{y}=\stackrel{\textit{connection fee}}{5}+\stackrel{\textit{over 5 mins fee}}{(x-5)0.10}
\\\\\\
\textit{how much can you get for 10 bucks? well if 10 bucks is the \underline{cost}}
\\\\\\
10=5+(x-5)0.1\implies 5=0.1(x-5)\implies \cfrac{5}{0.1}=x-5
\\\\\\
50=x-5\implies \stackrel{minutes}{55}=x[/tex]
