After eating a hearty meal they went to see the Buckingham palace. There, Rachel learned that 16 visitors came to the Buckingham palace on the previous day. If there were 33 visitors on that day How many more visitors visited the Buckingham palace on that day than on the previous day?
There were 16 visitors on the previous day. 
There were 33 visitors on that day. 

How many more visitors visited the Buckingham palace on that day than on the previous day?

There were 33 - 16 = 17 more visitors on that day than on the previous day.