=>2/5-x+4/3=1/2-1/5
=>6/15+20/15-x=3/10
=>26/15-x=3/10
=>x=52/30-9/30=43/30
<=> 2/5 - x + 4/3 = 3/10
<=> 2/5 - x = 3/10 - 4/3 = -31/30
<=> x = 2/5 - -31/30 = 43/30
\(\dfrac{2}{5}-x+\dfrac{4}{3}=\dfrac{1}{2}+\left(-\dfrac{1}{5}\right)\\ -x+\dfrac{26}{15}=\dfrac{3}{10}\\ -x=\dfrac{3}{10}-\dfrac{26}{15}\\ x=\dfrac{43}{30}\)
\(\left(\dfrac{2}{5}-x\right)-\left(-\dfrac{4}{3}\right)=\dfrac{1}{2}+\left(-\dfrac{1}{5}\right)\)
\(=\dfrac{2}{5}-x+\dfrac{4}{3}=\dfrac{1}{2}-\dfrac{1}{5}\)
\(=\dfrac{2}{5}-x+\dfrac{4}{3}=\dfrac{3}{10}\)
\(\dfrac{2}{5}-x=\dfrac{-31}{30}\)
\(x=\dfrac{43}{30}\)