En una granja hay 100 animales entre gallinas y conejos?

Respuesta : <img src="https://tex.z-dn.net/?f=%5Ctexttt%7BEl%20n%5C%27umero%20de%20gallinas%20es%20de%2064%20y%20el%20de%20conejos%20es%20de%2036%7D" />Explicación paso a paso : Llamando a x como el numero de gallinas e y el numero de conejos, entonces : <img src="https://tex.z-dn.net/?f=x%2By%3D100%5C%2C%5C%2C%5Ctexttt%7BLa%20suma%20total%20de%20animales%2C%20entre%20gallinas%20y%20conejos%7D%5C%5C%5C%5C2x%2B4y%3D272%5C%2C%5C%2C%5Ctexttt%7BEl%20numero%20total%20de%20patas%7D%5C%5C%5C%5C%5Ctexttt%7BLuego%20se%20tiene%20el%20siguiente%20sistema%3A%7D%5C%5C%5C%5C%5Cleft%5Clbrace%5Cbegin%7Barray%7D%7Brcl%7Dx%2By%26%3D%26100%5C%5C2x%2B4y%26%3D272%5Cend%7Barray%7D%5Cright.%5C%5C%5C%5C%5Ctexttt%7BPara%20resolver%20el%20sistema.%20usaremos%20el%20m%5C%27etodo%20de%20suma%20y%20resta%7D%5C%5C%5Ctexttt%7Bpara%20ello%20multiplicaremos%20la%20ecuaci%5C%27on%201%20por%20-2%7D%5C%5C%5Ctexttt%7Bobteni%5C%27endose%3A%7D%5C%5C%5C%5C%5Cleft%5Clbrace%5Cbegin%7Barray%7D%7Brcl%7D-2%28x%2By%26%3D%26100%29%5C%5C2x%2B4y%26%3D272%5Cend%7Barray%7D%5Cright.%3D%5Cleft%5Clbrace%5Cbegin%7Barray%7D%7Brcl%7D-2x-2y%26%3D%26-200%5C%5C2x%2B4y%26%3D272%5Cend%7Barray%7D%5Cright.%5C%5C%5C%5C%5Ctexttt%7BSumando%201%20y%202%20y%20resolviendo%20nos%20queda%3A%7D%5C%5C2y%3D72%5C%5Cy%3D%5Cfrac%7B72%7D%7B2%7D%3D36%5C%5C%5C%5C%5Ctexttt%7BSustituyendo%20el%20valor%20de%20y%20en%7D%5C%5C%5Ctexttt%7Bcualesquiera%20de%20las%20ecuaciones%7D%5C%5C%5Ctexttt%7Bpor%20ejemplo%201%20se%20obtiene%3A%7D%5C%5C%5C%5Cx%2B36%3D100%5C%5C%5C%5C%5Ctexttt%7BResolviendo%3A%7D%5C%5C%5C%5Cx%3D100-36%5C%5Cx%3D64%5C%5C%5C%5C%5Ctexttt%7BPor%20lo%20tanto%3A%7D%5C%5C%5C%5Cx%3D64%5C%5Cy%3D36" />Saludos.