a) \(x=\dfrac{1}{4}+\dfrac{2}{13}\)
=> \(x=\dfrac{13}{52}+\dfrac{8}{52}\)
=> \(x=\dfrac{21}{52}\)
b) \(\dfrac{x}{3}=\dfrac{2}{3}+\dfrac{-1}{7}\)
=> \(\dfrac{x}{3}=\dfrac{14}{21}+\dfrac{-3}{21}\)
=> \(\dfrac{x}{3}=\dfrac{11}{21}\)
=> \(x=\dfrac{11}{21}\)x \(3\)
=> \(x=\dfrac{11}{7}\)