Đáp án: 2. a) $\left \{ {{3x-2y=3} \atop {2x+2y=2}} \right.$
⇔ $\left \{ {{5x=5} \atop {2x+2y=2}} \right.$
⇔ $\left \{ {{x=1} \atop {y=0}} \right.$
b) $\left \{ {{3x-2y=3} \atop {2x+2y=2}} \right.$
(giống câu a)
c) $\left \{ {{5x+7y=6} \atop {4x-3y=2}} \right.$
⇔ $\left \{ {{20x+28y=24} \atop {-20x+15y=-10}} \right.$
⇔ $\left \{ {{43y=14} \atop {4x-3y=2}} \right.$
⇔ $\left \{ {{y=14/43} \atop {x=-10/43}} \right.$