`A = (\sqrt{7} + \sqrt{3})/(\sqrt{7} - \sqrt{3}) + (\sqrt{7}-\sqrt{3})/(\sqrt{7}+\sqrt{3})`
`= ((\sqrt{7} + \sqrt{3})^2)/((\sqrt{7}-\sqrt{3})(\sqrt{7}+\sqrt{3})) + ((\sqrt{7}-\sqrt{3})^2)/((\sqrt{7}+\sqrt{3})(\sqrt{7}-\sqrt{3}))`
`=(7+2\sqrt{21}+3)/(7-3) + (7-2\sqrt{21}+3)/(7-3)`
`=(10+2\sqrt{21}+10-2\sqrt{21})/4`
`=20/4`
`=5`