Option A
With partner alternating times:
50/35 calories of ski erg
30/24 calories of ski erg
15/12 calories of ski erg
Go hard pace on these, when its your turn.
Option B
With partner alternating times:
30 burpees
20 burpees
10 burpees
Go hard when its your turn to work.
If need to scale reps here is an options
30-20-10 calories of ski erg or 21-15-9 reps of burpees.