Răspuns :
[tex] \left \{ {{x+y=43} \atop {2x+4y=124}} \right. [/tex] ⇒ [tex] \left \{ {{y=43-x} \atop {2x+4(43-x)=124}} \right. [/tex] ⇒ [tex] \left \{ {{y=43-x} \atop {2x+172-4x=124}} \right. [/tex] ⇒ [tex] \left \{ {{y=43-x} \atop {2x-4x=124-172}} \right. [/tex] ⇒ [tex] \left \{ {{y=43-24} \atop {x=24}} \right. [/tex] ⇒ [tex] \left \{ {{y=19} \atop {x=24}} \right. [/tex] si pentru verificare [tex]\left \{ {{x+y=43} \atop {2x+4y=124}} \right. [/tex] ⇒ [tex] \left \{ {{24+19=43} \atop {2*24+4*19=124}} \right. [/tex]