With a running clock:
3 Rounds:
20 Calorie Bike/Row
20 Situps
3 Rounds:
20 Calorie Bike/Row
20 Kettlebell/Dumbbell Push Jerk
3 Rounds:
20 Calorie Bike/Row
20 Situps

This is meant to be one continuous workout. Make it more challenging by switching to GHD Situps