Answer:
300 minutes
Explanation:
Let
x----> the numbers of minutes used
y ---> the cost per month
we know that
First cell phone plan
y=0.15x+20 ---> equation A
Second cell phone plan
y=0.10x+35 ---> equation B
equate the equation A and equation B
0.15x+20=0.10x+35
Solve for x
0.15x-0.10x=35-20
0.05x=15
x=15/0.05
x= 300 minutes
Find the cost y
y=0.15(300)+20 =$65
That means
For x=300 minutes
The cost for both calling plans is y=$65