AHSME 1991 Problem 5

In the arrow-shaped polygon [see figure], the angles at vertices $A,C,D,E$ and $F$ are right angles, $BC=FG=5, CD=FE=20, DE=10$, and $AB=AG$. The area of the polygon is closest to $\text{(A) } 288 \text{(B) } 291 \text{(C) } 294 \text{(D) } 297 \text{(E) } 300$