Answer:
I think your question is to write WRITE A SYSTEM OF EQUATIONS in that situation.
And here is my answer:
Let y = the total cost
Let m - the number of minutes
1. The first choice is to pay $10.00 per month plus &0.09 per MB of data
<=> y = 0.09m + 10
2. The second choice is to pay $16.00 per month plus $0.07 per MB of data
<=> y = 0.07m + 16
So the system of equation is: