Easy Money [Extreme]: Bruce Wayne Predator: 3 Medals: Initiation DLC - Batman Arkham Origins

1st and 2nd Medals
Use the Caltrops to trip over the armored guy. Make sure you throw it in front of him or he wont trip over. Then jump down, drop the smoke pellet to safely take out the fallen armored guy to get the first medal and then take out the guy next to him for the second medal.
3rd Medal
While the other guys are converging onto your position, you may have time to take out an extra guy before setting up for your window takedown medal. There will be some guys running down the center next to the windows, but they tend to be too far away to get the window takedown. So you will have to zip kick down at least one guy next to the window and then wait for him to get up next to the window to clench the last medal.