Answer:
2.5 gallons
Step-by-step explanation:
Make the denominators of the fractions the same and combine them
[tex]\frac{1}{3} =\frac{2}{6}[/tex]
[tex]\frac{2}{6} +\frac{1}{6} =\frac{3}{6}[/tex]
Then simplify the fraction
[tex]\frac{3}{6} =\frac{1}{2}[/tex]
Then subtract how many gallons you have from how many you want
[tex]3 -\frac{1}{2} = 2\frac{1}{2}[/tex]
You will need 2.5 gallons to make 3 gallons