(7 - 3 7/11) - (4 - 2 3/11) = 1 7/11
1) 7 - 3 7/11 = 6 11/11 - 3 7/11 = 3 4/11
2) 4 - 2 3/11 = 3 11/11 - 2 3/11 = 1 8/11
3) 3 4/11 - 1 8/11 = 2 15/11 - 1 8/11 = 1 7/11
(8 - 4 13/20) - (6 - 5 3/20) = 2 1/2
1) 8 - 4 13/20 = 7 20/20 - 4 13/20 = 3 7/20
2) 6 - 5 3/20 = 5 20/20 - 5 3/20 = 17/20
3) 3 7/20 - 17/20 = 2 27/20 - 17/20 = 2 10/20 = 2 1/2