10/15=2/3
5/20=1/4
2/3=8=12 и 1/4=3/12
$$$$$$$
4/18=2/9
9/27=1/3
2/9=2/9 и 1/3=3/9
$$$$$$$$$
25/30=5/6
35/45=7/9
5/6=15/18
7/9=14/18
$$$$$$$$$$
130/150=13/15
21/30=7/10
13/15=26/30
7/10=21/30
$$$$$$$$$$$
24/42=4/7
30/78=5/13
4/7=52/91
5/13=35/91
$$$$$$$
25/60=1/4
9/15=3/5
1/4=5/20
3/5=12/20