Multiple Argument for IF statement

I'm creating a workbook that uses algorithms. I'm creating the algorithms with IF statements (this is the only way I know how to perform them).

Please see attached spreadsheet. I'm working on an IF statement that if the difference of D7 and C20 is 1 (cell B94 captures this total day)and the discharge disposition (D6) is either 4,6,or7 then it equals B217. I'm nesting the algorithm in cell M5.

Also, could a formula/statment be made in B94 to say if cells D7 is blank then B94 is blank?

Thanks for the help!