3/8 :5/7=3/8* 7/5=21/40
1/5 :3/4=1/5*4/3=4\15
4/5 :4/7=4/5 *7/4=7/5=1 ц 2/5
3/16 : 5/12=3/16 *12/5=9/20 ( сократили16 и 12 на 4)
3/5 :9/25=3/5 *25/9 =5/3=1 ц 2/3 (тут сократи 25 и 5) и 3 и 9
7\8:2=7/8* 1/2=7/16
3/8 :3=3/8 *1/3=1/8 ( троики сократи)
5 :2/5=5/1 *5/2=25/2= 12 ц 1/2
8 : 4/5=8/1 * 5/4= 10
3/7 :1/2 =3/7 *2/1=6/7