Ответ:
4/5:8=1/10; 5/6:10=1/12; 3/7:12=1/28; 4:2/5=10; 21:7/8=24; 25:5/8=40; 1/8:3/4=1/6
Пошаговое объяснение:
1. 4/5:8= 4/5:8/1= 4/5*1/8=4/40=1/10
2. 5/6:10= 5/6:10/1= 5/6*1/10= 5/60=1/12
3. 3/7:12= 3/7:12/1= 3/7*1/12= 3/84=1/28
4. 4:2/5= 4/1:2/5= 4/1*5/2= 20/2=10
5. 21:7/8= 21/1:7/8= 21/1*8/7=168/7=24/1=24
6. 25:5/8= 25/1:5/8= 25/1*8/5= 200/5=40/1=40
7. 1/8:3/4= 1/8*4/3= 4/24= 1/6