How Do You Calculate Percentage When One Number Is A Negative Number? If I Want To Show Growth Between 2 Quarters From -$4,000 (negative) To $1,000 (positive); How Do I Show It As A Percentage?

To find the percentage:-
First, you should find the difference between the negative and the positive numbers. Lets take your example. The difference between 2 quarters is
 1,000-(-4,000) = 1,000+4,000 = 5,000

Second, neglect the negative (-) sign of a negative number and apply the percentage formula.
Now
Difference = 5,000
Starting Value = 4,000
Percentage = (Difference/Starting value)x100%
                 = (5,000/4,000)x100%
                 = 1.25x100%
                 = 125%
                 
The increase in the second quarter from the first quarter is 125%

If Old figure < 0
Growth = -1 * (New figure - Old figure)/ Old figure
Else
Growth =   (New figure - Old figure)/ Old figure

OR

if (New figure   > Old figure
Growth =   ABS(New figure - Old figure)/ ABS(Old figure)
Else
Growth =   -1 * ABS(New figure - Old figure)/ ABS(Old figure)

The first Qtr. Loss of $160,000 to a profit the next Qtr. Of $725,000 equals what growth?