One smartphone plan costs $30 per month for talk and messaging and $8 per gigabyte of data used each month. A second smartphone plan costs $60 per month for talk and messaging and $3 per gigabyte of data used each month. Let c represent the total cost in dollars and d represent the amount of data used in gigabytes. The system of equations below can be used to represent this situation. Remember, d if for the amount of data and c is for the cost.

What would that cost be (c)?

How many gigabytes would have to be used for the plans to cost the same (d)?