The first group uses a total of 10 students * 2 markers = <<10*2=20>>20 markers.
The second group uses a total of 15 students * 4 markers = <<15*4=60>>60 markers.
This is a total of 20 + 60 = <<20+60=80>>80 markers.
The total number of markers in the boxes is 5 markers * 22 boxes = <<5*22=110>>110 markers.
This leaves 110 – 80 = <<110-80=30>>30 markers for the last group to split between themselves.
The last group is made up of 30 total students – 10 students in the first group – 15 students in the second group = <<30-10-15=5>>5 students.
Therefore, students in the last group receive 30 markers / 5 students = <<30/5=6>>6 markers each.
#### 6