`#tnvt`
`\frac{5\sqrt{3}-3\sqrt{5}}{\sqrt{5}-\sqrt{3}}+\frac{7}{4+\sqrt{15}}`
`=\frac{\sqrt{15}(\sqrt{5}-\sqrt{3})}{\sqrt{5}-\sqrt{3}}+\frac{7(4-\sqrt{15})}{(4-\sqrt{15})(4+\sqrt{15})}`
`=\sqrt{15}+\frac{7(4-\sqrt{15})}{4^2-\sqrt{15}^2}`
`=\sqrt{15}+\frac{7(4-\sqrt{15})}{16-15}`
`=\sqrt{15}+7(4-\sqrt{15])`
`=28+\sqrt{15}-7\sqrt{15}`
`=28-6\sqrt{15}`