1. a) 1+6x=13 <=> 6x=13-1=12 <=> x=12/6=2
b) 10x=70 <=> x=70/10 <=> x=7
c) x:(-8)=10 <=> x=-8×10 <=> x=-80
2. a) 3(2x+8)=-6 <=> 6x+24=-6 <=> 6x=-30 <=> x=-30/6 <=> x=-5
b) 5x+4=2x-8 <=> 3x=-12 <=> x=-12/3 <=> x=-4
c) 4(2-x)=x-2 <=> 8-4x=x-2 <=> -5x=-10 <=> x=-10/-5 <=> x=2
