Final answer:
The attack on Pearl Harbor occurred on December 7, 1941, and the September 11 attacks on the World Trade Center and Pentagon happened on September 11, 2001. There were 60 years between these two events.
Step-by-step explanation:
The attack on Pearl Harbor occurred on December 7, 1941, and the September 11 attacks on the World Trade Center and Pentagon happened on September 11, 2001. To calculate the number of years between these two events, we can subtract the year of Pearl Harbor from the year of 9/11: 2001 - 1941 = 60. Therefore, 60 years separated these two events.