a,`\frac{2}{3\sqrt{5}}=\frac{2\sqrt{5}}{3\sqrt{5}.\sqrt{5}}=\frac{2\sqrt{5}}{3.5}=\frac{2\sqrt{5}}{15}`
b,`\frac{\sqrt{2}-\sqrt{6}}{6\sqrt{2}}=``\frac{(\sqrt{2}-\sqrt{6})\sqrt{2}}{6\sqrt{2}.\sqrt{2}}`=`\frac{2-\sqrt{12}}{12}`
c,`\frac{1+\sqrt{2}}{1-\sqrt{2}}`=`\frac{1+\sqrt{2}}{1-\sqrt{2}}`=`\frac{(1+\sqrt{2})(1+\sqrt{2})}{(1-\sqrt{2})(1+\sqrt{2})}`==`\frac{(1+\sqrt{2})^2}{1-2}`=`\frac{1+2\sqrt{2}+2}{-1}`=`\frac{-3-2\sqrt{2}}{1}`
