Subtracting Fractions

Question 1:

2 5 - 1 5
1 5

Question 2:

5 7 - 2 7
3 7

Question 3:

3 4 - 2 4
1 4

Question 4:

13 20 - 1 2
3 20

Question 5:

15 20 - 7 10
1 20

Question 6:

7 10 - 4 20
10 20 = 1 2