A cell phone company charges $50 for the phone plus a monthly service charge for $30. The equation below describes the total cost y after x months. y = 30x + 50 which is true of the relationship between x and y?

To find total, we'll need to add all the costs! There's the cost for the phone which is paid once, monthly fee for all the months you use it.

total = 50 + (30 * months)

In this case, the question wants the equation in x and y, so we can plug those in:

y = 50 + 30x