Converse - you might need to go into more detail
52 weeks @ 2 (sat+sun) = 104. Where does the 120 come from average 10 days off a month or??
When taking leave do Crew take Mon-Fri (5 days) and have the Sat-Sun either side as off days which are part of the 120?.
Is the dispute over average days off per month or year. I can understand if days off are pro rata'd down when on leave / sick i.e. you couldn't expect to have 10 days off a month when you also have 2 weeks leave...
I don't know how much leave VS crews have but guessing at say 30 with 120 days off that seems low for a purely L/H roster (just back from JFK as a pax so sympathy high today..)