b) `(9\sqrt{5}+3\sqrt{27})/(\sqrt{5}+\sqrt{3})`
`=(9\sqrt{5}+9\sqrt{3})/(\sqrt{5}+\sqrt{3})`
`=(9(\sqrt{5}+\sqrt{3}))/(\sqrt{5}+\sqrt{3})`
`=9`
d) `\sqrt{3+\sqrt{5}}-\sqrt{3-\sqrt{5}}-\sqrt{2}`
`=(\sqrt{2}\sqrt{3+\sqrt{5}})/(\sqrt{2})-(\sqrt{2}\sqrt{3-\sqrt{5}})/(\sqrt{2})-\sqrt{2}`
`=\sqrt{6+2\sqrt{5})/(\sqrt{2})-(\sqrt{6-2\sqrt{5}})/(\sqrt{2})-\sqrt{2}`
`=(\sqrt{(\sqrt{5}+1)^2})/(\sqrt{2})-(\sqrt{(\sqrt{5}-1)^2})/(\sqrt{2})-\sqrt{2}`
`=(|\sqrt{5}+1|)/(\sqrt{2})-(|\sqrt{5}-1|)/(\sqrt{2})-\sqrt{2}`
`=(\sqrt{5}+1)/(\sqrt{2})-(\sqrt{5}-1)/(\sqrt{2})-\sqrt{2}`
`=(\sqrt{5}+1-\sqrt{5}+1)/(\sqrt{2})-\sqrt{2}`
`=(2)/(\sqrt{2})-\sqrt{2}`
`=(2.\sqrt{2})/(\sqrt{2}.\sqrt{2})-\sqrt{2}`
`=(2\sqrt{2})/(2)-\sqrt{2}`
`=\sqrt{2}-\sqrt{2}`
`=0`
