x is the number of minutes per month. The plans are equal when
[tex].24 x = 44.95 + .10 x[/tex]
[tex].14 x = 44.95[/tex]
[tex]x = 44.95/.14 = 321 \frac 1 {14} \textrm{ minutes}[/tex]
Assuming they round to the nearest minute, 322 minutes per month or more for the second plan to be preferable.