\(\Leftrightarrow\dfrac{4x}{5}-45^0=arccot\left(-\dfrac{1}{2}\right)+k180^0\)
\(\Leftrightarrow\dfrac{4x}{5}=45^0+arccot\left(-\dfrac{1}{2}\right)+k180^0\)
\(\Leftrightarrow x=56,25^0+\dfrac{5}{4}arccot\left(-\dfrac{1}{2}\right)+k225^0\) (\(k\in Z\))