a) 9-2x=x+3<=>-2x-x=3-9<=>-3x=-6l:(-3)<=>x=+2=2
b)3(x+2)-1=x-7<=>3x+6-1=x-7<=>3x-x=-7-6+1<=>2x=-12l:2<=>x=-6
c)4(2x+1)-(11-2 x 3)x=6<=>8x+4-5x=6<=>8x-5x=6-4<=>3x=2l:3<=>x=2 supra 3
Nu prea am inteles a treia ecuatia,adica nu am inteles scrierea dar sper sa te fii ajutat ;)