I literally am so cofused

The ratio on the lines state: gallons to cups is 4:64
This means for every 4 gallons, there are 64 cups. If you divide 64 by 4 you get 16.
Now you know for every 1 gallon, there are 16 cups.
Multiply 16 by 3 so you can figure out how many cups there will be for every 3 gallons.
The answer is 48 cups. For every 3 gallons, there will be 48 cups.