9x(7x-6)-18x 7a-6(19-a) 0.8(6x-2)+1.6(x-4) 2.8(5b--8a)×1.2 .9-5..1c-5.6) 8/9(2 1/4a-3/4b)-7/30(4 2/7a-8 4/7b)

9x(7x-6)-18x=63х-6-18х=45х-6
7a-6(19-a)=7а-114+6а=13а-114
0.8(6x-2)+1.6(x-4)=4.8х-1.6+1.6х-6.4=6.4х-8
2.8(5b-6a)-(7b-8a)×1.2=14b-16.8a-7b+8a=7b-8.8a
-(-4.9-5.8c)-(3.1c-5.6)=4.9+5.8с-3.1с+5.6=10.5+2.7с