4/5÷8; = 4/5 * 1/8 = 1/5 * 1/2 = 1/10 = 0,1
3/7÷12; = 3/7 * 1/12 = 1/7 * 1/4 = 1/28
21÷7/8; = 21/1 * 8/7 = 3/1 * 8/1 = 24
8÷16/21; = 8/1 * 21/16 = 1/1 * 21/2 = 10 1/2 = 10,5
1/8÷3/4; = 1/8 * 4/3 = 1/2 * 1/3 = 1/6
1/2÷9; = 1/2 * 1/9 = 1/18
2/5÷7; = 2/5 * 1/7 = 2/35
3/4÷9/16 = 3/4 * 16/9 = 1/1 * 4/3 = 4/3 = 1 1/3