1. (2 1/4 + 4 5/6) : 3 2/5 - 3/4 : 3/5 = 5/6,
1) 2 1/4 + 4 5/6 = 9/4 + 29/6 = 27/12 + 58/12 = 85/12 = 7 1/12,
2) 7 1/12 : 3 2/5 = 85/12 : 17/5 = 85/12 * 5/17 = 25/12 = 2 1/12,
3) 3/4 : 3/5 = 3/4 * 5/3 = 5/4 = 1 1/4,
4) 2 1/12 - 1 1/4 = 25/12 - 5/4 = 25/12 - 15/12 = 10/12 = 5/6,
2. (5 8/9 : 1 17/36 + 1 1/4) * 5/21 = 1 1/4,
1) 5 8/9 : 1 17/36 = 53/9 : 53/36 = 53/9 * 36/53 = 36/9 = 4
2) 4 + 1 1/4 = 5 1/4,
3) 5 1/4 * 5/21 = 21/4 * 5/21 = 5/4 = 1 1/4,
3. (4 2/5 * 5/8 + 12 3/7 : 4 5/6 - 8 1/2 : 14) : 33/56 = 8,
1) 4 2/5 * 5/8 = 22/5 * 5/8 = 22/8 = 2 3/4,
2) 12 3/7 : 4 5/6 = 87/7 : 29/6 = 87/7 * 6/29 = 18/7 = 2 4/7,
3) 8 1/2 : 14 = 17/2 * 1/14 = 17/28,
4) 2 3/4 + 2 4/7 - 17/28 = 11/4 + 18/7 - 17/28 = 77/28 + 72/28 - 17/28 = 132/28 = 4 5/7,
5) 4 5/7 : 33/56 = 33/7 * 56/33 = 56/7 = 8