i worked the following example

column E F
row 4 3 2
5 4 3
6 5 4

in a4
=((INDIRECT("E"&ROW(A4))-INDIRECT("F"&ROW(A4)))/INDIRECT("F"&ROW(A4)))

in b4
=(E4-F4)/F4

copied down thru row 6

results

column A B
row 4 0.5 0.5
5 0.33 0.33
6 0.25 0.25

both formulas are number and equivilent