Add a '+' to a formula showing positive variance

Am looking for a way to get my variance functions to show a plus sign in front of them (I know they do this regardless for a minus)

For example's sake:
A1= actual profit margin (say 24%)
A2= budgeted profit margin (say 20%)

I want the variance cell (=A1-A3) to show '+4%'

Thanks in advance for any help!!!