P Q R S is a square with side length 60 and centre C. Point W lies on P S so that W S=53. Point X lies on S R so that X R=40. The midpoint of Q R is Y. Point Z lies on P Q. What is the length of Z Q so that the total area of the shaded regions is equal to the total area of the non-shaded regions?
Answer Choices
A. 21
B. 15
C. 23
D. 19
E. 17