\(-\dfrac{3}{10}+\dfrac{5}{18}:x=\left(-\dfrac{1}{5}\right)^2\\ =>-\dfrac{3}{10}+\dfrac{5}{18}:x=\dfrac{1}{25}\\ =>\dfrac{5}{18}:x=\dfrac{1}{25}+\dfrac{3}{10}\\ =>\dfrac{5}{18}:x=\dfrac{17}{50}=>x=\dfrac{17}{50}\text{×}\dfrac{5}{18}=\dfrac{17}{180}\)
