Subtracting Mixed Numbers

Question 1:

4 7 10 - 3 1 2
12 10 = 1 2 10 = 1 1 5

Question 2:

5 4 5 - 3 3 4
41 20 = 2 1 20

Question 3:

5 5 9 - 1 1 8
319 72 = 4 31 72

Question 4:

5 1 2 - 3 1 3
13 6 = 2 1 6