a)
|(-3)^{-3}|=|(-\frac{1}{3})^3|=|-\frac{1}{27}|=\frac{1}{27}
|2-4^{\frac{1}{2}}|=|2-\sqrt4|=|2-2|=0
|\sqrt5-2|=\sqrt5-2
b)
|2-\sqrt5|=-(2-\sqrt5)=-2+\sqrt5=\sqrt5-2
|27^{\frac{1}{3}}-\sqrt3|=|\sqrt[3]{27}-\sqrt3|=3-\sqrt3
|2^{-3}-3^2|=|(\frac{1}{2})^3-9|=|\frac{1}{8}-9|=|-8\frac{7}{8}|=8\frac{7}{8}