
Solution:
Given PRQ is a triangle.
ST is a line parallel to RQ.



<u>Triangle proportionality theorem,</u>
<em>If a line parallel to one side of a triangle intersects the other two sides, then it divides the two sides proportionally.</em>


Do cross multiplication, we get

Divide by 2x on both sides, we get

I think its 6 but im not sure to be exactly right
(a)

= 400
(b)


(c) Only the positive solution makes sense because you cannot have a negative side length.
(d) Since one side of the painting is 20 inches, all four sides together will be 20*4 = 80 inches