`13) 1/(\sqrt5 -\sqrt3) + (5\sqrt3 -3\sqrt5)/(2\sqrt15) - 10/(\sqrt5)`

`=(\sqrt5+\sqrt3)/(5-3) + (\sqrt5.\sqrt3. (\sqrt5 - \sqrt3))/(2\sqrt3 . \sqrt5) - (10\sqrt5)/5`

`=(\sqrt5+\sqrt3)/2 + (\sqrt5-\sqrt3)/2 - 2\sqrt5`

`=(\sqrt5 +\sqrt3 +\sqrt5 -\sqrt3)/2 - 2\sqrt5`

`=(2\sqrt5)/2 - 2\sqrt5`

`=\sqrt5 -2\sqrt5`

`=-\sqrt5`

`14) (3\sqrt2 -2\sqrt3)/(\sqrt3 -\sqrt2) - 10/(1+\sqrt6) + 2 \sqrt(3/2)`

`=(\sqrt2 .\sqrt3 (\sqrt3 -\sqrt2))/(\sqrt3 -\sqrt2) - (10(1-\sqrt6))/(1-6) + (2\sqrt3 .\sqrt2)/2`

`=\sqrt6 - (10(1-\sqrt6))/(-5) +\sqrt6`

`=\sqrt6 +2(1-\sqrt6) +\sqrt6`

`=2\sqrt6 +2 -2\sqrt6`

`=2`