a]
[tex]2(x+3)=12+x\\\\2x+6=12+x\\\\2x-x=12-6\\\\\huge\boxed{x=6}[/tex]
b]
[tex]3(2-x)+2=3-\frac{1}{2}(x+1) \ \ |\cdot2\\\\6(2-x)+4=6-(x+1)\\\\12-6x+4=6-x-1\\\\-6x+x=6-1-12-4\\\\-5x=-11 \ \ |:(-5)\\\\\huge\boxed{x=2,2}[/tex]
