1) 10,5:0,25= 10 1/2:25/100= 10 1/2:1/4=21/2*4/1=42
2) 127,2:0,4=127 2/10:4/10=127 1/5:2/5=636/5*5/2=318
3) 18 1/7:0,5=127/7:5/10=127/7:1/2=127/7*2/1=254/7=36 2/7
4) 9,15:3 1/3=9 15/100:10/3=9 3/20:10/3=183/20*3/10=549/200=2 149/200
5) 17 1/3:8 5/6=52/3:53/6=52/3*6/53=104/53=1 51/53
6) 4 5/7:2 1/35=33/7:71/35=33/7*35/71=33/1*5/71=165/71=2 23/73
А*(2*5)=а*10
а=75
а*10=750
а=750
а*10=7500
а=7500
а*10=75000
1200-х+387=0
-х=-387-1200
-х=-1587
х=1587