How many grades can my empa pull my grade down by?

It will reduce whatever you got overall by 20%. If you got 80% overall, then you will get 60% which is a C.

If the unit is worth 20% then it's worth 20%. Your total grade will get pulled down by 20%.

So say if I managed to get a D in the empa how much would that pull my grade down by?

If the unit is worth 20% then it's worth 20%. Your total grade will get pulled down by 20%.

I don't think that's how it works, if she doesn't get any marks then that's it, it just doesn't count towards the total, it doesn't pull her marks down any further

OP, your EMPA marks will be scaled to UMS, and assuming you get no marks (worst case scenario) that would mean you can then only get 80% max that year, so if you got 100% in all your other exams then you can only just scrape an A grade. If you get something like 50% in your EMPA, that will mean you've amassed 10% for your total UMS so to get an A (80%) you would need 88% average in the rest of your exams

That's what I said . The Empa doesn't "pull you down", it just means you will get less.

so just to clear things up:
If I get 2 not low but not super high As, what is the minimum grade I could get in my EMPA to keep it at an A/B?

Assuming the lowest A's you can get so 80% on both of your other exams:

So that's (0.8*0.8)=0.64 of your total UMS (64%)

You need 80% total for an A, 70% for a B.

You'd need an A in your EMPA to get an A overall
To get a B overall you'd need 30% (surely that's below a U..)

Assuming 85% average:
(0.85*0.80)=0.68 = 68%

To get a B you would need 2% more for your total UMS
That means you need 10% in your EMPA

To get an A, you'd need 60 in your EMPA (a C)

That's so helpful thank you!! what about for 90%?