variable based on profit you stand to make based back bet

[color=rgba(35, 40, 44, 0.9)]in formula builder is there variable: The profit you stand to make based  back bet ? example if i place back bet at 5.5 odds for 100 i would win = 450 any idea ?

back amount * (back price - 1)
But to be more accurate:
back amount * (back price - 1) * (1 - commission / 100)