1) (2/7 + 5/21) : 1 4/7
(6/21 + 5/21) : 11/7
11/21 : 11/7 = 11/21 * 7/11 = 7/21 = 1/3
2) (8/11 + 3/22) : 5/11
(16/22 + 3/22) : 5/11
19/22 : 5/11 = 19/22 * 11/5 = 19/10
3) 1 7/12 : (3/8 + 5/12)
19/12 : (9/24 + 10/24)
19/12 : 19/24 = 19/12 * 24/19 = 24/12 = 2
4) 17/36 : (7/12 - 5/9)
17/36 : (21/36 - 20/36)
17/36 : 1/36 = 17/36 * 36/1 = 17/1 = 17
5) (3/14 + 5/7) : 3 5/7
(3/14 + 10/14) : 26/7
13/14 : 26/7 = 13/14 * 7/26 = 1/2 * 1/2 = 1/4
6) 19/24 : (3/16 + 5/24)
19/24 : (9/48 + 10/48)
19/24: 19/48 = 19/24 * 48/19 = 2/1 = 2