So we just need to do some conversions. We can convert gallons (gal)---> liters (L) just using a few conversion factors and some simple stoichiometry.
Here are the conversion factors:
1 gal= 3.78541 L
Here is how to do the problem:
12 gal x 3.78541 L/1 gal = 45.4249 L
The final answer with significant figures (there are two significant figures) is:
45 L