can someone plz help for brainliest

Answer: part 1 multiplying part 2 the answer is 15000 but I don't know what scientific notation means tell me in comments
Step-by-step explanation:
Answer:
5.4 * 10^5
Step-by-step explanation:
We are multiplying to find this one.
Each second 15000 gallons of water flows.
There are 3600 seconds in an hour
15000 * 3600 = 54000000
54000000 in scientific notation is 5.4 * 10^5