Lets first find the slope:
(y₂-y₁)=m(x₂-x₁)
(-9-(-3)) = m(-4-6)
-6 = m(-10)
Isolate m:

=

-10 and -10 cancels out

= m

= m
Now we know the slope, which is

The equations is
y = mx + c
Take any two coordinates from the given above
Im taking (6,-3)
Plug in those coordinates and the slope to the formula
-3 =

(6) + c
-3 =

+ c
Isolate c
-3 -

= c

= c
which gives us:
-6.6 = c
Now plug in the slope and c in the equation:
y =
x+ (-6.6)or
y =
x +(-
)