By doing base times area that is what I will do
So we are trying to get the “y” alone, so to undo the division by -8, we will multiply both sides by -8, then simplify.
(-8) y/(-8) = (-8) 1/16
y = -8/16
and simplified:
y = -1/2
If rectangle and triangle are attached ....so
area of rectangle will be L×W
and area of triangle will be .5 × b×h
as we know both are attached then base would be equal to width
..so b=W !!!
On the opposite side of Point A
In this case you would set it up as

(180 represents the degree of the triangle)
Add up like terms

Subtract 130 to the other side (180-130)

Divide 10 to the other side ( 50/10)
.

Hope this was clear :)