Answer:
For more than 180 minutes of phone use.
Explanation:
Let m represent number of minutes of phone use in a month.
We have been given that in Plan A, there is no monthly fee, but the customer pays $0.06 per minute of use.
The cost of using m minutes in plan A would be [tex]0.06m[/tex].
We are also told that in Plan B, the customer pays a monthly fee of $4.80 and then an additional $0.03 per minute of use.
The cost of using m minutes in plan B would be [tex]0.03m+4.80[/tex].
To find the amounts of monthly phone when Plan A will cost more than Plan B, we will set cost of plane A greater than cost of plan B as:
[tex]0.06m>0.03m+4.80[/tex]
Let us solve for m.
[tex]0.06m-0.03m>0.03m-0.03m+4.80[/tex]
[tex]0.03m>4.80[/tex]
[tex]\frac{0.03m}{0.03}>\frac{4.80}{0.03}[/tex]
[tex]m>180[/tex]
Therefore, Plan A will cost more than Plan B for more than 180 minutes of phone use.