\((\dfrac{-5}{18}).\dfrac{-9}{10}=\dfrac{-50}{180}.\dfrac{-162}{180}=\dfrac{8100}{180}=45\)
\((\dfrac{-1}{4})^2.\dfrac{4}{11}+\dfrac{7}{11}.(\dfrac{-1}{4}^2)=(\dfrac{-1}{16}).\dfrac{4}{11}+\dfrac{7}{11}.(\dfrac{-1}{16})=(\dfrac{-1}{16}).(\dfrac{4}{11}+\dfrac{7}{11})=(\dfrac{-1}{16}).1=\dfrac{-1}{16}\)