Answer:
The number of minutes in a month must be equal to 50 minutes
Step-by-step explanation:
Let
x ---> the number of minutes
we have
Cost Plan A
[tex]3x+100[/tex]
Cost Plan B
[tex]5x[/tex]
we know that
In order for plan A cost the same than plan B, the following equation must hold true.
cost of plan A = cost of plan B
substitute
[tex]3x+100= 5x[/tex]
solve for x
[tex]5x-3x=100\\2x=100\\x=50\ min[/tex]
therefore
The number of minutes in a month must be equal to 50 minutes