Given the task definition and input, reply with output. You are given a math word problem and you are supposed to only use subtraction on the numbers embedded in the text to answer the following question and then only report the final numerical answer.

Context: After eating a hearty meal they went to see the Buckingham palace. There, Rachel learned that 45 visitors came to the Buckingham palace on the previous day. If 829 people visited the Buckingham palace within the past 85 days 

 Question: How many visitors visited the Buckingham palace on that day?

784