Question

Solve the system by substitution.-x+3y=20 7y=x

Answer 1

`\begin{gathered} -x+3y=20\ldots\ldots\ldots\ldots...(1)_{} \\ 7y=x\ldots\ldots.\ldots\ldots\ldots\ldots.....(2) \\ -7y+3y=20 \\ -4y=20 \\ \text{divide both sides by -4} \\ y=(20)/(-4) \\ y=-5 \\ 7y=x \\ 7*-5=x \\ x=-35 \end{gathered}`