Final answer:
Lyndon B. Johnson came into office after John F. Kennedy was assassinated.
Step-by-step explanation:
According to the terms set out by the Constitution, in case of the removal, death or resignation of the President, the Vice President becomes the President. After the assassination of John F. Kennedy, Lyndon B. Johnson became the President of the United States. Kennedy was assassinated on November 22, 1963, in Dallas, Texas, and Johnson, who was the Vice President at the time, was sworn in as the 36th President later that same day.