(7х-9)-(11-х)=12
7х-9-11+х=12
7х+х=12+11+9
8х=32
х=4
2)= -9с²+9с²+d²-d²=0
4)= (7b-t)(7b+t)+49b²+t²=49b²-t²+49b²+t²=98b²
6) =121c²+9-(11c²+66c)=121c²+9-11c²-66c=110c²+9-66c
1) -0.3*(0.8-0.6)=-0.3*0.2=-0.06
2) -0.4*(3/11-8/11)=-0.4*(-5/11)=2/11
3) 4/9*(-7/8+1/8)=4/9*(-6/8)=4/9*(-3/4)=-1/3
4) 2 2/9*(3.7-(-5.3))=2 2/9*(3.7+5.3)=2 2/9*9=20/9*9=20