Rút gọn biểu thức

Bài 1: Rút gọn:
a) $$\begin{gathered} a) 3\sqrt{\frac{20}{49}}-5\sqrt{\frac{5}{4}+}\sqrt{\frac{500}{16}} \\ b) \left(2\sqrt{15}+6\sqrt{27}\right)÷\sqrt{3}-18 \\ c) \left(4\sqrt{12}+\sqrt{108}-9\right)÷2\sqrt{3} \\ d) 5xy\sqrt{\frac{25x^2}{y^6} }với \mathrm{x}<0, \mathrm{y}>0 \\ \mathrm{e}) 0,2{\mathrm{x}}^3{\mathrm{y}}^3\sqrt{\frac{16}{{\mathrm{x}}^4{\mathrm{y}}^8}} \mathrm{với} \mathrm{x}\ne 0, \mathrm{y}\ne 0 \\ \mathrm{Bài} 2: \mathrm{Tìm} \mathrm{x}, \mathrm{biết}: \\ \mathrm{a}) \sqrt{3}. {\mathrm{x}}^2-12=0 \\ \mathrm{b}) \frac{{\mathrm{x}}^2}{\sqrt{5}}-\sqrt{20}=0 \\ \mathrm{c}) \sqrt{3}.\mathrm{x}+\sqrt{3}=\sqrt{12}+\sqrt{27} \end{gathered}$$
giải giúp mik vs ak!!!