Subtracting Mixed Numbers

Question 1:

2 3 4 - 2 1 9
23 36

Question 2:

3 7 8 - 3 7 9
7 72

Question 3:

5 1 10 - 1 7 9
299 90 = 3 29 90

Question 4:

5 1 2 - 2 5 6
16 6 = 2 4 6 = 2 2 3