1)
[tex]\frac{a}{48} = 2\\\\a = 48\cdot2\\\\\boxed{a = 96}[/tex]
2)
[tex]\frac{10}{4a} = 6\\\\\frac{5}{2a} = 6\\\\6\cdot2a = 5\\\\12a = 5 \ \ \ /:12\\\\\boxed{a = \frac{5}{12}}[/tex]
3)
[tex]\frac{16}{a} = 20\\\\20a = 16 \ \ \ /:20\\\\\boxed{a = \frac{4}{5}}[/tex]
4)
[tex]\frac{4a^{2}}6} = 12\\\\\frac{2a^{2}}{3} = 12\\\\2a^{2} = 36 \ \ \ /:2\\\\a^{2} = 18\\\\a = \sqrt{18} = \sqrt{9\cdot2}=\sqrt{9}\cdot\sqrt{2} \\\\\boxed{a = 3\sqrt{2}}[/tex]
