Given 2 angle : 45 and 90 (right angle)
==> 180-45-90 = 45
Compute the slope of the line through (-2, -9) and (-4, -17):

Any line perpendicular to this line will have slope -1/4. The one that passes through (0, 10) satisifes

The slope is 0, the equation is y=50
When the line is horizontal the slope is 0 and when the line is vertical the slope is undefined.
Hope this makes sense, x = 75!!
-8=-(x+4)
remember the invisible 1
-8=-1(x+4)
distribute using distributeiv porpety
a(b+c)=ab+ac
-1(x+4)=-x-4
-8=-x-4
add 4 to both sides
-4=-x
mutily both sides by -1
4=x