(12y+30)(1,4-0,7)=0
16,8y-8,4y+42-21=0
8,4y+21=0
8,4y= -21
y= -21/8,4
y= -2,5
9x-(5x-4)=4x+4
9x-5x+4=4x+4
4x+4=4x+4
4x-4x=4-4
x=0
Арифметическая прогрессия
1) 1/6+1/18*3/4= 1/6+1/24=4/24+1/24=5/24
2) 203/48*6/7-13/9= 29/8-13/9= 261/72-104/72=157/72= 2 13/72
3) (16/24+15/24-22/24) *16/3= 9/24*16*/3= 9*16/24*3= 3*4/6*1= 12/6=2
4) 15 4/7-35/8*(50/35-34/35)= 15 4/7-35/8*16/35=15 4/7-35*16/8*35= 15 4/7-2= 13 4/7