a: \(\Leftrightarrow\left(\dfrac{1}{4}\cdot x\right):3=\dfrac{5}{6}:\dfrac{1}{8}=\dfrac{5}{6}\cdot8=\dfrac{40}{6}=\dfrac{20}{3}\)
=>1/4x=20
=>x=80
b: \(\Leftrightarrow\dfrac{2}{3}:0.1x=\dfrac{4}{3}\cdot\dfrac{5}{4}=\dfrac{5}{3}\)
=>\(x\cdot\dfrac{1}{10}=\dfrac{2}{3}:\dfrac{5}{3}=\dfrac{2}{5}\)
=>x=2/5:1/10=2/5x10=4