Ta có: \(A=25\%-1\frac{1}{2}+0,5\cdot2\frac{2}{5}\)
\(=\frac{1}{4}-\frac{3}{2}+\frac{1}{2}\cdot\frac{12}{5}\)
\(=\frac{1}{4}-\frac{6}{4}+\frac{6}{5}\)
\(=\frac{-25}{20}+\frac{24}{20}=\frac{-1}{20}\)
\(A= \) 25%-\(1\dfrac{1}{2}\)+0,5.2\(\dfrac{2}{5} \)
= \(\dfrac{1}{4}-\dfrac{3}{2}+\dfrac{1}{2}.\dfrac{12}{5}\)
\(= \dfrac{1}{4}-\dfrac{3}{2}+\dfrac{6}{5}\)
\(= \dfrac{-1}{20}\)