a, \(\dfrac{4x}{7}=\dfrac{1}{5}+\dfrac{2}{3}=\dfrac{13}{15}\Rightarrow60x=91\Leftrightarrow x=\dfrac{91}{60}\)
b, \(\dfrac{4}{5}+\dfrac{5}{7x}=\dfrac{1}{6}\Rightarrow\dfrac{5}{7x}=-\dfrac{19}{30}\Rightarrow7x\left(-19\right)=150\Leftrightarrow x=\dfrac{150}{7\left(-19\right)}=-\dfrac{150}{133}\)
a: =>4/7x=1/5+2/3=3/15+10/15=13/15
hay x=91/60
b: =>5/7:x=1/6-4/5=-19/30
hay x=-150/133