Answer
$y=-x$ (red graph)
$y=x$ (blue graph)
Work Step by Step
Linear equations of the form $y=mx+b$ has a $y$-intercept of $b$ and a slope of $m.$ Hence, the given equation, $
y=-x
$ has
\begin{align*}
y\text{-intercept: }&
0
\\\text{Slope: }&
-1\text{ or } \dfrac{-1}{1}
.\end{align*}
To graph the equation, start at the $y-$intercept of $(
0,0
)$. Then use the notion of the slope as $\dfrac{rise}{run}.$ Since the slope is $
\dfrac{-1}{1}
,$ then $rise=
-1
$ and $run=
1
.$ Hence, from the $y$-intercept, go down by $rise=
-1
$ unit then go to the right by $run=
1
$ unit. This results to the point $(
-1,1
)$. By connecting this point and the $y$-intercept, the graph of $
y=-x
$ (red graph) is determined.
Similarly, the other given equation, $
y=x
$ has
\begin{align*}
y\text{-intercept: }&
0
\\\text{Slope: }&
1\text{ or } \dfrac{1}{1}
.\end{align*}
The $y-$intercept is $(
0,0
)$. Using the notion of the slope as $\dfrac{rise}{run},$ then $rise=
1
$ and $run=
1
.$ Hence, from the $y$-intercept, go up by $rise=
1
$ unit then go to the right by $run=
1
$ unit. This results to the point $(
1,1
)$. By connecting this point and the $y$-intercept, the graph of $
y=x
$ (blue graph) is determined.