a)
[tex]\left \{ {{x-3(y-2x)=4x-3} \atop {2x-y=2}} \right. \\\\\left \{ {{x-3y+6x=4x-3} \atop {-y=-2x+2\ |*(-1)}} \right. \\\\\left \{ {{3x-3y=-3} \atop {y=2x-2}} \right. \\\\\left \{ {{3x-3(2x-2)=-3} \atop {y=2x-2}} \right. \\\\\left \{ {{3x-6x+6=-3} \atop {y=2x-2}} \right. \\\\\left \{ {{-3x=-9\ |:(-3)} \atop {y=2x-2}} \right. \\\\\left \{ {{x=3} \atop {y=2*3-2}} \right. \\\\\left \{ {{x=3} \atop {y=4}} \right.[/tex]
b)
[tex]\left \{ {{2(x+y)-4=3(x-y)} \atop {4(x+y)-4=7(x-y)}} \right. \\\\\left \{ {{2x+2y-4=3x-3y} \atop {4x+4y-4=7x-7y}} \right. \\\\\left \{ {{-x+5y=4\ |*(-3)} \atop {-3x+11y=4}} \right. \\\\\left \{ {{3x-15y=-12} \atop {-3x+11y=4}} \right|+\\\\\left \{ {{-4y=-8\ |:(-4)} \atop {-3x+11y=4}} \right.\\\\\left \{ {{y=2} \atop {-3x+11*2=4}} \right.\\\\\left \{ {{y=2} \atop {-3x+22=4}} \right.[/tex]
[tex]\left \{ {{y=2} \atop {-3x=-18\ |:(-3)}} \right.\\\\\left \{ {{y=2} \atop {x=6}} \right.\\\\\left \{ {{x=6} \atop {y=2}} \right.[/tex]
