Here is an example I did of the problem hope it helps let me know if you need anything else~!
~<span>Cecildoesscience </span>

Please consult the "Calculations" section of this ans .

The information we're given is below :
- slope : -1/3
- Point crossed by the line : (3, 6)
As per given information , we can do the following :
- Write the line's equation in point slope form
Point - slope form looks like so :
y-y₁=m(x-x₁)
y-6=-1/3(x-3)
y-6=-1/3x+1
y=-1/3x+1+7
y=-1/3x+6
↑ 

Answer: B (-12, 15)
Step: (3×-4) =-12
And (3×5)= 15
The slope intercept it (0,4)
The sum of measures of angles A and B is 90°
Hence the angles are complementary
- As complementary angles have sum 90°