Answer :
Answer:
470 minutes
Explanation:
Let the number of minutes of phone used in a month = m
Plan A
The customer pays 6 cents per minute of use.
Therefore, the total cost for plan A = 0.06m
Plan B
The customer pays a monthly fee of $9.40 and then an additional 4 cents per minute of use.
Therefore, the total cost for plan B = 9.40+0.04m
If plan A costs at least as much as plan B, then we have:
[tex]0.06m\ge9.40+0.04m[/tex]We then solve for m.
[tex]\begin{gathered} 0.06m-0.04m\ge9.40 \\ 0.02m\ge9.40 \\ m\ge\frac{9.40}{0.02} \\ m\ge470 \end{gathered}[/tex]When you use the phone for at least 470 minutes, the amount of monthly phone use for plan A will cost at least as much as plan B.