Ateacher has a 2-gallon (32-cup) container of juice. she gives each student 1/2 cup of juice. which equation represents the amount of juice that remains, y, after x students are served?

The amount of juice that remains, y, is the difference from the initial amount of juice and the amount distributed to the students. If each x students get 0.5 cup each, then 0.5x cups of juice have been distributed. The equation for the remaining amount is, 
                                    y = 32 - 0.5x

Iam guessing c. or d.