Joy started with 2.75 gallons of milk. she used 1.5 pints to make mashed potatoes and another cup to make cookies. how much milk does joy have left?

Unit conversions:
1 pint = 0.125 gallons
1 cup = 0.0625 gallons

Now,
Total volume of milk = 2.75 gallons
Milk used for mashed potato = 1.5 pints = 1.5*0.125 = 0.1875 gallons
Milk used for  cookies = 1 cup = 1*0.0625 = 0.0625 gallons

Milk left = 2.75 - 0.1875 - 0.0625 = 2.5 gallons