Answer :
We can translate this question as follows:
[tex]0.08x+5.95=17.15[/tex]Then, we need to solve the equation for x (number of minutes):
[tex]0.08x=17.15-5.95\Rightarrow0.08x=11.2\Rightarrow x=\frac{11.2}{0.08}\Rightarrow x=140[/tex]Therefore, Tiffany talked on the phone for 140 minutes.