Rationalize each denominator.
a. $\frac{3}{\sqrt{5}-\sqrt{2}}$
b. $\frac{2 \sqrt{5}}{2 \sqrt{5}+3 \sqrt{2}}$
c. $\frac{\sqrt{3}-\sqrt{2}}{\sqrt{3}+\sqrt{2}}$
d. $\frac{2 \sqrt{5}-8}{2 \sqrt{5}+3}$
e. $\frac{2 \sqrt{3}-\sqrt{2}}{5 \sqrt{2}+\sqrt{3}}$
f. $\frac{3 \sqrt{3}-2 \sqrt{2}}{3 \sqrt{3}+2 \sqrt{2}}$