Subtract: 7 gal 2 qt 1 pt – 5 gal 3 qt ½ pt

I'm stuck plz help.

7 gal 2 qt 1 pt – 5 gal 3 qt ½ pt

6 gal 6 qt 1 pt - 5 gal 3 qt ½ pt = 1 gal 3 qt 1/2 pt