I have a spreadsheet where I am trying to do two things:

First: I want to create a forumula in column "Z" that looks at the
number in column "Y" and if it's a negative, then multiply the number
in column "X" by 1.1.  If the number in column "Y" is a positive
number, then just insert the number in column "X".  So:

    Column X number is $100
    Column Y number is -20%
    Column Z number would be $110

    Column X number is $100
    Column Y number is 20%
    Column Z number would be $100

Second: In column AA, I want to perform a concatenate if the number in
column "Y" is a negative.  So:

    Column Y number is -20%, then =concatenate(a1,a2,a3,a4)

TIA,
Robert