Question

I have a math test tomorrow and I need help on this.

Answer 1

The given system of equations is

`\begin{gathered} x=y\rightarrow(1) \\ x-3y=4\rightarrow(2) \end{gathered}`

To solve this system by substitution, substitute x in equation (2) by y

`y-3y=4`

Now add the like terms on the left side

`\begin{gathered} (y-3y)=4 \\ -2y=4 \end{gathered}`

Divide both sides by -2

`\begin{gathered} (-2y)/(-2)=(4)/(-2) \\ y=-2 \end{gathered}`

Substitute the value of y in equation (1) to find x

`x=-2`

The solution of the system is (-2, -2)