Problem 399

Harriet has a square piece of paper. She folds it in half to form a rectangle and then in half again to form a second rectangle (which is not a square). The perimeter of the second rectangle is $30\text{ cm}$. What is the area of the original square? (A) $36\text{ cm}^2$ (B) $64\text{ cm}^2$ (C) $81\text{ cm}^2$ (D) $100\text{ cm}^2$ (E) $144\text{ cm}^2$