\(\dfrac{3}{12}-\left(\dfrac{6}{12}-\dfrac{3}{10}\right)=\dfrac{3}{12}-\dfrac{6}{12}+\dfrac{3}{10}=\dfrac{3.5-6.5+3.6}{60}=\dfrac{3}{60}=\dfrac{1}{20}\)
\(\dfrac{3}{12}-\left(\dfrac{6}{12}-\dfrac{3}{10}\right)\)
\(=\dfrac{3}{12}-\dfrac{6}{12}+\dfrac{3}{10}\)
\(=\dfrac{-3}{12}+\dfrac{1}{10}\)
\(=\dfrac{-1}{4}+\dfrac{1}{10}\)
\(=\dfrac{-10}{40}+\dfrac{4}{40}\)
\(=\dfrac{-6}{40}\)
\(=\dfrac{-3}{20}\)
\(\dfrac{3}{12}-\left(\dfrac{6}{12}-\dfrac{3}{10}\right)\)
\(=\dfrac{3}{12}-\dfrac{6}{12}+\dfrac{3}{10}\)
\(=-\dfrac{3}{12}+\dfrac{3}{10}\)
\(=-\dfrac{15}{60}+\dfrac{18}{60}\)
\(=\dfrac{3}{60}\)\(=\dfrac{1}{20}\)