#LC
e, `2/(\sqrt5-\sqrt3) - (5+\sqrt15)/(\sqrt5+\sqrt3)`
= `(2\sqrt5+2\sqrt3)/(5-3) - (\sqrt5(\sqrt5+\sqrt3))/(\sqrt5+\sqrt3)`
= `\sqrt5 + \sqrt3-\sqrt5`
= `\sqrt3`
f, `(\sqrt18 + \sqrt12)/(\sqrt3+\sqrt2)+(5)/(\sqrt6-1)`
= `(\sqrt6(\sqrt3 + \sqrt2))/(\sqrt3+\sqrt2)+(5(\sqrt6+1))/(6-1)`
= `\sqrt6 + \sqrt6 + 1`
= `1+2\sqrt6`