Endurance WOD Workout

In teams of two alternate 3 rounds of both amraps:
A): 4 min amrap:
3 min run or bike + double unders rest of the time
– 2 min rest –

B): 4 min amrap:
20/15 ski or row
10 back extensions
15 air squats
20 sit ups
– 2 min rest –