Пожалуйста! Надеюсь, что помогла!
1) 1.2x+21-3.2x+12=2
-2x+33=2
-2x=2-33
-2x= -31
x= 31/2
2) 4.5*7/15х+4.5*2/9-0.77*8/11х+0.77*3/7= -1.75
3/10*7х+5/5-7/25*2х+11/100*3= -1.75
21/10х+1-14/25х+33/100= -1.75
105х-28х/50+1+33/100= -1.75
77х/50+1+33/100= -1.75
1.54х+100+33/100= -1.75
1.54х+133/100= -1.75
1.54х+1.33= -1.75
1.54х= -1.75-1.33
1.54х= -3.08
х= -2
28х-х= 0,729
27х= 0,729
х= 0.027
ответ:х= 0.027
-0.6(5-3m-1.4n)+2(6+2m-1.3n)=-3+1,8m+0.84n+18+4m-2.6n=15+5.8m-1.76n