Answer:
1.125 gallons
Explanation:
The first thing you do here is convert 9 quarts to gallons. To convert from quarts to gallons you dvide by 4. So 9/4=2.25.
The next thing you do is divide this number by two to achieve your answer
2.25/2=1.125
So the final answer you would be after using half of his paint Gary is left with 1.125 gallons of paint