[ASK] how do you calculate these odds

hi i'm not sure if i posted it in the right section but since it's my first time here i hope its ok

in football/soccer i see a market called HT or FT odds

i'm trying to workout how to calculate these odds but can't find the right formula

i know it's not a matter of dutching FT odds with HT odds but i can't figure what parameters to use

so lets say H@2.3 D@3.5 A@3.45 how would you calculate odds for this market

an example would be much appreciated

thanks again

Shaz :o