1) 4/5 : 2/5 = 4/5 * 5/2 = 4/2 = 2,
2) 6/7 : 3/7=6/7*7/3=6/3=2,
3) 4/9:1/9=4/9*9/1=4,
4) 6/11 : 3/11=6/11*11/3=6/3=2,
5) 12/13 : 4/13 = 12/13 * 13/4=12/4=3,
6) 16/17:8/17=16/17*17/8=16/8=2,
7) 1/7:1/5=1/7*5/1=5/7,
8) 1/13 : 1/8=1/13*8/1=8/13,
9) 3/7 : 3/4=3/7*4/3=4/7,
10) 2/5 : 0,4 = 2/5 : 4/10 = 2/5*10/4 = 1,
11) 3/5 : 0,6=3/5:6/10=3/5*10/6=1,
12) 1,5 : 3/2 = 15/10:3/2=15/10*2/3=1