Answer :
[tex]y-y_1=m(x-x_1)\\\\
y-(-6)=-\dfrac{1}{2}(x-6)\\
y+6=-\dfrac{1}{2}x+3\\
y=-\dfrac{1}{2}x-3[/tex]
[tex]You\ can\ just\ plug\ this\ into\ point-slope\ equation: \\ (y-y1)=m(x-x1)\ \ \ \ m\ is\ slope \\ \\ (y-(-6)= \frac{-1}{2}(x-6) \\ \boxed{y+6= \frac{-1}{2}(x-6) } \\ \\ If\ you\ want\ in\ slope-intercept\ form: \\ y+6= \frac{-1}{2}(x-6) \\ y+6= \frac{-1}{2}x+3 \\ \boxed{ y=- \frac{1}{2}x-3 }[/tex]