We will have the following:
From the information provided we will have that:
Plan A:
[tex]y=0.08m+20[/tex]Plan B:
[tex]y=0.06m+24.60[/tex]Now, we will determine the value as follows:
[tex]\begin{gathered} 0.08m+20=0.06m+24.60\Rightarrow0.02m=4.6 \\ \\ \Rightarrow m=230 \end{gathered}[/tex]So, the number of minutes for which plan A costs less than plan B is 230.
[tex]m<230[/tex]