[tex]\it a)\ 5x-2(x+1)=x+5 \Rightarrow 5x-2x-2=x+5 \Rightarrow 5x-2x-x=5+2 \Rightarrow \\ \\ \Rightarrow 2x=7\Big|_{:2} \Rightarrow x=3,5\\ \\ \\ b)\ 7(x+3)-5=6(x-1)+21 \Rightarrow 7x+21-5=6x-6+21 \Rightarrow \\ \\ \Rightarrow 7x-6x=-6+21-21+5 \Rightarrow x=-1[/tex]
[tex]\it c)\ 6x-3(x+2)=7(x+1)-17 \Rightarrow 6x-3x-6=7x+7-17 \Rightarrow \\ \\ \Rightarrow 6x-3x-7x=7-17+6 \Rightarrow -4x=-4 \Rightarrow x=1[/tex]
