$\text{a)}$

$\sqrt{\frac{2}{3}}\cdot \left(-3\sqrt{\frac{2}{3}}+4\sqrt{0,375}\right)=\sqrt{\frac{2}{3}}\cdot \left(-3\sqrt{\frac{2}{3}}\right)+\sqrt{\frac{2}{3}}\cdot 4\sqrt{0,375}=$

 

$=-3\cdot \sqrt{\frac{2}{3}\cdot \frac{2}{3}}+4\cdot \sqrt{\frac{2}{3}\cdot 0,375}=-3\sqrt{\frac{4}{9}}+4\sqrt{\frac{2}{{\sout{3}}^1}\cdot \frac{{\sout{3}}^1}{8}}=$

$=-3\cdot \frac{2}{3}+4\sqrt{\frac{1}{4}}=-2+4\cdot \frac{1}{2}=-2+2=0$

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$\text{b)}$

$\left(4\sqrt[3]{72}-6\sqrt[3]{1125}\right)\cdot 2\sqrt[3]{\frac{1}{9}}=4\sqrt[3]{72}\cdot 2\sqrt[3]{\frac{1}{9}}-6\sqrt[3]{1125}\cdot 2\sqrt[3]{\frac{1}{9}}=$

$=8\sqrt[3]{72\cdot \frac{1}{9}}-12\sqrt[3]{1125\cdot \frac{1}{9}}=8\sqrt[3]{8}-12\sqrt[3]{125}=$  

$=8\cdot 2-12\cdot 5=16-60=-44$