Answer:
12 units
Step-by-step explanation:
Because the two triangles are similar:

Hope this helps!
EDIT: MY ANSWER ASSUMED CONSTANT ACCELERATION - CHANGING IT NOW
XY is the rightmost side of the rectangle. Since you have the image already graphed, you can just <u>count</u> how many units there are from X to Y.
If you are starting at point X and you walk to point Y, how many "lines" do you cross to get there?
Answer: 4 units
* means multiply, sqrt=radical
expand
-10+sqrt2*8i-sqrt2*15+24i
group
(-10-sqrt2*15)+(sqrt2*8+24)i
not exactly sure though