\(=\dfrac{7}{20}-\dfrac{1}{4}=\dfrac{7}{20}-\dfrac{5}{20}=\dfrac{1}{10}\)
\(\dfrac{7}{20}+\dfrac{-1}{4}=\dfrac{7}{20}+\dfrac{-5}{20}=\dfrac{2}{20}=\dfrac{1}{10}\)
\(\dfrac{7}{20}+\left(-\dfrac{1}{4}\right)=\dfrac{7}{20}-\dfrac{1.5}{4.5}=\dfrac{7-5}{20}=\dfrac{2}{20}=\dfrac{1}{10}\)
\(\dfrac{7}{20}+\dfrac{\left(-1\right).5}{4.5}=\dfrac{7}{20}+\dfrac{-5}{20}=\dfrac{2}{20}=\dfrac{1}{10}\)