Still on Batteries, but New question

Normally I am good at maths, but help me out please. I have just bought a 120a/h deep cycle battery and have a 12 volt fridge that allegedly drags max of 2.7 amps, and there are 3 x21 watt 12v lights. I f i used all at once, how long could i expect to get out of the battery time wise if start off fully charged. Likelihood of running 3 lights at once is higly unlikely, is more likely to be running a 300w inverter off the battery along with 1 light and the fridge. I have come up withperfect scenario of 21 - 23 hrs, but realise battery will wind down to an unuseable voltage before time runs out( at least unuseable for the fridge............................................. by the way i joined as a member because of the excellent help you people have already given me.....Thx in anticipation of more help