4【2x-1]-2[10x+1]=3[2x+1]-12
8x-4-20x-2=6x+3-12
8x-20x-6x=4+2-12
-18x=-6
x=1/3
0.3x+0.7[200-x]=108
0.3x+140-0.7x=108
0.3x-0.7x=108-140
-0.4x=-32
x=80