Answer
$\text{slope-intercept form: }
y=-2x+18
\\\\
\text{standard form: }
2x+y=18$
Work Step by Step
Using $y-y_1=m(x-x_1)$ or the point-slope form of linear equations, the equation of the line passing through $(
5,8
)$ and with a slope of $m=
-2
$ is
\begin{array}{l}\require{cancel}
y-8=-2(x-5)
.\end{array}
In the form $y=mx+b$, the equation above is equivalent to
\begin{array}{l}\require{cancel}
y-8=-2x+10
\\\\
y=-2x+10+8
\\\\
y=-2x+18
.\end{array}
In the form $Ax+By=C$, the equation above is equivalent to
\begin{array}{l}\require{cancel}
y=-2x+18
\\\\
2x+y=18
.\end{array}
Hence, the different forms of the equation of the line with the given conditions are
\begin{array}{l}\require{cancel}
\text{slope-intercept form: }
y=-2x+18
\\\\
\text{standard form: }
2x+y=18
.\end{array}