I'm not sure this is possible or if I'm even going about it the right way...
but I'd like to know if there is a function (or combination of functions)
that I could insert into the DISCOUNTED PRICE column to determine whether to
multiply or subtract the DISCOUNT from the PRICE, depending on what is
entered in the DISCOUNT column. Some discounts are a percentage and some are
dollars off, so I need the spreadsheet to be capable of knowing which type of
discount is entered to return the correct DISCOUNTED PRICE result.

PRICE DISCOUNT DISCOUNTED PRICE
$50.00 *.1
$50.00 -10

I could also set it up with columns differentiating between a percentage
discount and a "dollars off" discount, but how do I set up a DISCOUNTED PRICE
function that would know which column has data in it and whether to multiply
or subtract the data?

PRICE % OFF $ OFF DISCOUNTED PRICE
$50.00 10%
$50.00 $10.00

Am I making this more complicated than it has to be?