Question

efetue a equaçao 11-7y=13-8y

Answer 1

$11-7y=13-8y~\text{(some (-13+8y) em ambos os lados da igualdade)}\\\\\\11-7y+(-13+8y)=13-8y+(-13+8y)\\\\\\11-7y-13+8y=13\hspace{-10}\diagdown-8y\hspace{-10}\diagup-13\hspace{-10}\diagdown+8y\hspace{-10}\diagup\\\\\\-2+y=0~~\text{(some 2 em ambos os lados da igualdade)}\\\\\\-2\hspace{-7}\diagup+2\hspace{-7}\diagup+y=0+2\\\\\\\large\fbox{ y=2 }$