a: \(-\dfrac{2}{5}+\dfrac{4}{5}x=\dfrac{3}{5}\)
=>\(\dfrac{4}{5}x=\dfrac{3}{5}+\dfrac{2}{5}=1\)
=>\(x=1:\dfrac{4}{5}=\dfrac{5}{4}\)
b; \(-\dfrac{3}{7}-\dfrac{4}{7}:x=-2\)
=>\(\dfrac{4}{7}:x+\dfrac{3}{7}=2\)
=>\(\dfrac{4}{7}:x=2-\dfrac{3}{7}=\dfrac{11}{7}\)
=>\(x=\dfrac{4}{7}:\dfrac{11}{7}=\dfrac{4}{11}\)