This workout is done in teams of 4. Within that team of 4, you will work in pairs. One pair (Pair A) runs 400m while the other pair (Pair B) starts on the AMRAP. Pair B starts with 5 rope climbs, but only one person may work at a time. Switch off whenever is needed. If you finish the rope climbs, move on to the 25 box jump-overs in similar fashion. When Pair A comes in from the run, they take over the work while Pair B goes out for the 400m run. Your score as a team will be rounds + reps.
For scaling, do 3 rope pulls for every rope climb. If you need to do single unders, just do a 1:1 ratio (i.e. count each single under as a double under for counting purposes). The box jump overs simply mean you need to jump from one side of the box to the other. You do not have to open your hips on top of the box. You may jump completely over a box, but your feet must be higher than the top of the box (i.e. no “splits” around the box).

AMRAP in 20 minutes in teams of 4:
5 rope climbs
25 box jump overs, 24/20″
50 sit-ups
75 KB swings, 53/35#
100 double unders
while running 400m