Y*4.9=2.94
y=2.94 : 4.9
y=0.6
0.6*4.9=2.94
2.94=2.94
y*0.7=0.0091
y=0.0091:0.7
y=0.013
0.013*0.7=0.0091
0.0091=0.0091
y:2,3=5,6
y=2.3*5.6
y=12.88
12.88 : 2.3=5.6
5.6=5.6
X*2:5+87*4=428
x*2:5+348=428
x*2:5=428-348=80
x*2=80*5=400
x=400:2=200
2-3(2+3x)=14
2-6-9x=14
-4-9x=14
-9x=14+4
-9x=18
x=-2
Раскрываем скобки х-12=-32, х=-32+12=-20
-х=27,3-15,3, х=-12