1) 6(x-4)=4(y+3)
6x-24=4y+12
6x-4y=12+24
2(3x-2y)=36
3x-2y=36/2
3x-2y=18
2) 6(x-4)-4(y+3)=3.8
6x-24-4y-12=3.8
6x-4y-36=3.8
6x-4y=3.8+36
6x-4y=39.8
(3x-2y)=39.8/2
(3x-2y)=19.9
3) -(3y+7)=8-2(8-y)
-3y-7=8-16+2y
-3y-2y=-8+7
-5y=-1
y=-1/-5
y=0.2
4) -2(2-5x)=2(x-3)-5
-4+10x=2x-6-5
10x-2x=-11+4
8x=-7
x=-7/8