AHSME 1995 Problem 22

A pentagon is formed by cutting a triangular corner from a rectangular piece of paper. The five sides of the pentagon have lengths $13, 19, 20, 25$ and $31$, although this is not necessarily their order around the pentagon. The area of the pentagon is $\mathrm{(A) \ 459 } \mathrm{(B) \ 600 } \mathrm{(C) \ 680 } \mathrm{(D) \ 720 } \mathrm{(E) \ 745 }$