Subtracting Fractions

Question 1:

6 7 - 2 7
4 7

Question 2:

6 10 - 5 10
1 10

Question 3:

2 4 - 1 4
1 4

Question 4:

4 8 - 1 5
12 40 = 3 10

Question 5:

3 5 - 1 2
1 10

Question 6:

19 20 - 4 8
18 40 = 9 20