⇔$\left \{ {{2(2-3y)-3y=4} \atop {x=2-3y}} \right.$
⇔$\left \{ {{4-6y-3y=4} \atop {x=2-3y}} \right.$
⇔$\left \{ {{4-9y=4} \atop {x=2+3y}} \right.$
⇔$\left \{ {{9y=0} \atop {x=2-3y}} \right.$
⇔$\left \{ {{y=0} \atop {x=2}} \right.$
vậy hpt có nghiệm $\left \{ {{y=0} \atop {x=2}} \right.$
