A square of cardboard is taped at the perimeter by a piece of ribbon 20cm long. What is the area of the board?
Rationalize the denominator of the expression \(\frac{6 + 2\sqrt{5}}{4 - 3\sqrt{6}}\)
Simplify \(\frac{5^x \times 25^{x - 1}}{125^{x + 1}}\)