=>3/10-3/2x-3/10x+3/4=9/20
=>-18/10x=9/20-3/4-3/10=-3/5
=>9/5x=3/5
=>x=1/3
\(c,\dfrac{3}{4}\cdot\left(\dfrac{2}{5}-2x\right)-\dfrac{3}{5}\cdot\left(\dfrac{1}{2}x-\dfrac{5}{4}\right)=\dfrac{9}{20}\)
\(\Rightarrow\dfrac{3}{10}-\dfrac{3}{2}x-\dfrac{3}{10}x+\dfrac{3}{4}=\dfrac{9}{20}\)
\(\Rightarrow x\cdot\left(-\dfrac{3}{2}-\dfrac{3}{10}\right)=\dfrac{9}{20}-\dfrac{3}{4}-\dfrac{3}{10}\)
\(\Rightarrow x\cdot\left(-\dfrac{9}{5}\right)=-\dfrac{3}{5}\)
\(\Rightarrow x=-\dfrac{3}{5}:\left(-\dfrac{9}{5}\right)=\dfrac{1}{3}\)
\(\dfrac{3}{4}\left(\dfrac{2}{5}-2x\right)-\dfrac{3}{5}\left(\dfrac{1}{2}x-\dfrac{5}{4}\right)=\dfrac{9}{20}\)
\(\Rightarrow\dfrac{3}{10}-\dfrac{3}{2}x-\dfrac{3}{10}x+\dfrac{3}{4}=\dfrac{9}{20}\)
\(\Rightarrow x\cdot\left(-\dfrac{3}{2}-\dfrac{3}{10}\right)=\dfrac{9}{20}-\dfrac{3}{10}-\dfrac{3}{4}\)
\(\Rightarrow x\cdot-\dfrac{9}{5}=-\dfrac{3}{5}\)
\(\Rightarrow x=-\dfrac{3}{5}:-\dfrac{9}{5}\)
\(\Rightarrow x=\dfrac{3}{5}\cdot\dfrac{5}{9}\)
\(\Rightarrow x=\dfrac{3}{9}\)
\(\Rightarrow x=\dfrac{1}{3}\)
