The slope of the given line is 5 because that's the coefficient of x.
Then, we use the following formula to find the perpendicular slope.
[tex]\begin{gathered} m=-\frac{1}{m_1} \\ m=-\frac{1}{5} \end{gathered}[/tex]Then, we use the point-slope formula.
[tex]\begin{gathered} y-y_1=m(x-x_1)_{} \\ y-3=-\frac{1}{5}(x-(-10))_{} \\ y-3=-\frac{1}{5}(x+10) \\ y=-\frac{1}{5}x-2+3 \\ y=-\frac{1}{5}x+1 \end{gathered}[/tex]