1/8 * 1 5/7 : 2 8/21 = 0,09
1) 1/8 * 1 5/7 = 1/8 * 12/7 = 12/56
2) 12/56 : 2 8/21 = 12/56 : 50/21 = 12/56 * 21/50 = 36/400 = 9/100 = 0,09
1 5/6 * 3 3/5 : 2 1/5 = 3
1) 1 5/6 * 3 3/5 = 11/6 * 18/5 = 33/5 = 6 3/5
2) 6 3/5 : 2 1/5 = 33/5 : 11/5 = 33/5 * 5/11 = 33/11 = 3