I think its a proper fraction.
Answer:
-1.
Step-by-step explanation:
1) according to the DeMoivre's theorem:

2) if cos(π)=-1 and sin(π)=0, then cosπ+i*sin(π)=-1.
Answer:
12 gallons
Step-by-step explanation:
If it takes 20 h for 5 gallons to be filled, it takes 4 h for 1 gallon to be filled. This is the ratio. You multiply 4 h by 12 to get 48 h, so you multiply 1 gallon by 12 as well. This is 12 gallons.