Resolver utilizando el método de sustitucion ​?

Respuesta : Explicación paso a paso : <img src="https://tex.z-dn.net/?f=%5Ctextbf%7BEl%20sistema%20es%3A%7D%5C%5C%5C%5C%5Cleft%5Clbrace%5Cbegin%7Barray%7D%7Brcl%7Dx%2By%26%3D%268%5C%5C3x-y%26%3D%2612%5Cend%7Barray%7D%5Cright." /><img src="https://tex.z-dn.net/?f=%5Ctextbf%7BLuego%20despejamos%20x%20o%20y%20en%20cua%21lquiera%20de%20las%20ecuaciones%7D%5C%5C%5Ctextbf%7Belegiremos%20y%20de%201%20y%20nos%20queda%3A%7D%5C%5C%5C%5Cy%3D8-x" /><img src="https://tex.z-dn.net/?f=%5Ctextbf%7BSustituyendo%20el%20valor%20de%20y%20en%20cualquiera%7D%5C%5C%5Ctextbf%7Bde%20las%20ecuaciones%2Cpor%20ejemplo%202%20nos%20queda%3A%7D%5C%5C%5C%5C3x-%288-x%29%3D12%5C%5C%5Ctextbf%7BDesarrollamos%20y%20simplificamos%7D%5C%5C3x-8%2Bx%3D12%5C%5C3x%2Bx%3D12%2B8%5C%5C4x%3D20%5C%5Cx%3D%5Cfrac%7B20%7D%7B4%7D%3D5" /><img src="https://tex.z-dn.net/?f=%5Ctextbf%7BSustituyendo%20el%20valor%20de%20x%2C%7D%5C%5C%5Ctextbf%7Bpor%20ejemplo%20en%201%20%28puede%20ser%20cualquiera%29%20obtenemos%3A%7D%5C%5C5%2By%3D8%5C%5Cy%3D8-5%5C%5Cy%3D3%5C%5C%5Ctextbf%7BAs%5C%27i%20la%20soluci%5C%27on%20del%20sistema%20es%3A%7D%5C%5Cx%3D5%5C%5Cy%3D3" />.