Pls help me and dint just say random pls

How do you summarize data in a two-way frequency table?

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible