I am currently trying to work out pass percentages for my course work at university

The course work consists of 2 different pieces of work that are marked separately
the first course work piece is worth 20% and the second is worth 80%.

In the first coursework I got 17% out of the possible 20%

The second course work is marked in two parts
The first part is out of 22- of which I got 12
The second part is out of 30 - which I havenít received a mark for yet

What mark do I need to get in the second part of the second course work to get an overall
mark of 50% for both course works combined?

Any help would be appreciated