Calculate gain/loss percentage in Numbers

I'm using Numbers Version 3.5.3

Is there a formula, or a series of formulas, that would allow me to calculate the gain/loss between to columns as a percentage?

For example:

In this chart I would want to fill the Loss/Gain column with an equation that would yield a %10 percent loss (indicated with red letters maybe) in the first row of the loss/gain column, a %120 percent gain (indicated with black letters) in the second row of the loss/gain column, and so on.

Thanks for any help!