7x - 10y = 10 primera ecuacion3x + 5y = - 20 segunda ecuacionComo resolverlo en el metodo de sustitucio?

<img src="https://tex.z-dn.net/?f=%5Cbegin%7Bcases%7D%267x-10y%3D10%5Cquad%5CLongrightarrow%5C%20Ecuaci%5C%27on%5C%201%5C%5C%263x%2B5y%3D-20%5Cquad%5CLongrightarrow%5C%20Ecuaci%5C%27on%5C%202%5Cend%7Bcases%7D%5C%5C%20%5C%5C%20%5C%5C%5Ctextbf%7BDespejamos%5C%20la%5C%20%22y%22%5C%20en%5C%20la%5C%20ecuaci%5C%27on%5C%202%5C%20y%5C%20reemplazamos%5C%20en%5C%20la%7D%5C%5C%5Ctextbf%7Becuaci%5C%27on%5C%201%3A%7D%5C%5C%20%5C%5Cy%3D%20%5Cdfrac%7B-20-3x%7D%7B5%7D%5C%5C%20%5C%5C%5Ctextbf%7BEntonces%3A%7D" />

<img src="https://tex.z-dn.net/?f=7x-10%5Cleft%28%20%5Cdfrac%7B-20-3x%7D%7B5%7D%5Cright%29%3D10%5C%5C%20%5C%5C%20%5C%5C7x%5C%20-%5Cnot%7B10%7D%5Cleft%28%20%5Cdfrac%7B-20-3x%7D%7B%5Cnot%7B5%7D%7D%5Cright%29%3D10%5Cquad%5Cto%5C%20Simplificamos%5C%20sacando%5C%20la%5C%20quinta.%5C%5C%20%5C%5C%20%5C%5C7x-2%28-20-3x%29%3D10%5C%5C%20%5C%5C7x%2B40%2B6x%3D10%5C%5C%20%5C%5C13x%2B40%3D10%5C%5C%20%5C%5C13x%3D10-40%5C%5C%20%5C%5C13x%3D-30%5C%5C%20%5C%5Cx%3D-%20%5Cdfrac%7B30%7D%7B13%7D%5Cquad%5Cto%5Cboxed%7BEl%5C%20primer%5C%20resultado.%7D" />

<img src="https://tex.z-dn.net/?f=%5Ctextbf%7BSustitu%5C%27imos%5C%20lo%5C%20que%5C%20dio%5C%20%22x%22%5C%20en%5C%20la%5C%20ecuaci%5C%27on%5C%202%3A%7D%5C%5C%20%5C%5C3%5Cleft%28-%20%5Cdfrac%7B30%7D%7B13%7D%5Cright%29%2B5y%3D-20%5C%5C%20%5C%5C3%28-30%29%2B13%285y%29%3D13%28-20%29%5C%5C%20%5C%5C-90%2B65y%3D-260%5C%5C%20%5C%5C%20%5Cdfrac%7B-90%2B65y%3D-260%7D%7B5%7D%5C%5C%20%5C%5C-18%2B13y%3D-52%5C%5C%20%5C%5C13y%3D-52%2B18%5C%5C%20%5C%5C13y%3D-34%5C%5C%20%5C%5Cy%3D-%20%5Cdfrac%7B34%7D%7B13%7D%5Cquad%5Cto%5Cboxed%7BEl%5C%20segundo%5C%20resultado.%7D%5C%5C%20%5C%5C%20%5C%5C%5Cmathbb%7BRESPUESTAS%3A%7D%5C%5C%20%5C%5C%5Cboxed%7B%5Cboxed%7B%5Cboldsymbol%7Bx%3D-%20%5Cdfrac%7B30%7D%7B13%7D%5C%20%3B%5C%20y%3D-%20%5Cdfrac%7B34%7D%7B13%7D%20%7D%7D%7D%5C%5C%20%5C%5C%20%5C%5C%5Ctextbf%7BMUCHA%5C%20SUERTE...%21%21%7D" />.