1. There are 100 fish in two aquariums combined. When 30 fish were moved from the first aquarium and 40 from the second, the number of fish left in each aquarium was equal. How many fish were originally in each aquarium?
Answer: 45 and 55 fish respectively.

Solution: After the relocation, there were 100-30-40=30 fish left in the aquariums. This means 15 in each. Therefore, there were initially $15+30=45$ fish in the first one, and $15+40=55$ fish in the second one.