In the diagram, P Q R S is a rectangle with S R=15. Point T is above P S and point U is on P S so that T U is perpendicular to P S. If P T=10 and U S=4 and the area of P Q R S is 180 , what is the area of \triangle P T S ?
Answer Choices
A. 60
B. 36
C. 48
D. 24
E. 12