How do I make the numerical value of column "a" postive or negative based on
the text value of column "b"

For example:

$126,513.00 c
$5,616,156.00 d
$132.00 d
$156.00 d
$55,444.00 c

When I upload the data all numbers come up positive. I would like it to
make it so the number comes up negative if column b contains a "c" and
positive if it contains a "d". I am willing to have to create a function in
row c and have the numbers in "a" move to column "c".