Opportunity to work as a student at Germany:
120 full days*8hours = 960 hours
240half days*4 hours = 960 hours
So monthly if it is 80 hours per month then after 12 months it is 12*80 = 960 hours
Monthly salary if it is = 11 euro/per hour
So 80 hours*11=880 euro per month
How you calculate 80 hours?
Okay, 80 hours = 20 hours per week,so if a month has 4 week then 20*4=80 hours per month.
Laws: https://www.gesetze-im-internet.de/aufenthg_2004/__16.html