Answer:
20.0%
Explanation:
The last 30 presidents of America starts from the 16th president, Abraham Lincoln and ends with the current and 45th president, Donald Trump.
The presidents that are 60 and above years during this period include
Donald Trump, Goerge H. W. Bush, Roland Regan, Gerald Ford, Dwight D. Eisenhower and Harry S. Truman.
Making 6 of them out of 30
The percentage is given by
Number of presidents aged 60 and above×100/Total number of presidents
6×30/100=20%