1) 4 1/5:7/15:1/3= 21/5*15/7*3/1 (21:7=3, 15:5=3)= 3*3*3=27;
2) 4 1/5:(7/15:1/3)= 21/5:(7/15*3/1)= 21/5:7/5= 21/5*5/7= 21/7= 3;
3) (5 8/9:1 17/36+1 1/4):4 1/5= (53/9:53/36+5/4):21/5= (53/9*36/53+5/4):21/5= (4+5/4)*5/21= (16/4+5/4)*5/21= 21/4*5/21= 5/4= 1 1/4;
4) (2 1/4+4 5/6):3 2/5-3/4:3/5= (9/4+29/6):17/5-3/4*5/3= ((9*3+29*2)/12)*5/17-5/4= ((27+58)/12)*5/17-5/4= 85/12*5/17-5/4= 17*5/12*5/17-5/4= 25/12-5/4= (25-15)/12= 10/12= 5/6.
1473 x-y=3
y=2x
y=3-2x
x=x-y
y=1x
x=xy
y=1xy
Ответ: -12 1/3*3=-37/3*3/3=-12 1/3
1 сторона- ×
2 сторона- ×+3,5
3 сторона -×-2,7
Р=27,8
×+×-+3,5+×-2,7=27,8
3×=27
×=27÷3
×=9 см - 1 сторона
9+3,5=12,5 см- 2 сторона
9-2,7=6,3 см- 3 сторона