a) \(\dfrac{-21}{15}\).\(\dfrac{-10}{14}\)            b)\(\left(-\dfrac{2}{3}\right)^2\)        c)\(\dfrac{-3}{4}\).\(\dfrac{-4}{5}\).\(\dfrac{16}{9}\)          d)\(\dfrac{-8}{3}\).\(\dfrac{5}{6}\)         e)\(\dfrac{16}{30}\).\(\dfrac{5}{12}\)        f) \(\dfrac{13}{30}\).\(\dfrac{-1}{5}\)                 g)\(\dfrac{2}{21}\).\(\dfrac{3}{28}\)           h)\(\left(\dfrac{-3}{4}\right)^3\)

tìm x, biết:

e) \(\dfrac{2}{7-x}\)=\(\dfrac{18}{45}\)       f)\(\dfrac{2x+3}{3}\)=\(\dfrac{50}{15}\)        g)\(2\dfrac{x}{7}\)=\(\dfrac{75}{35}\)         h)\(2\dfrac{3}{x}\)=\(\dfrac{13}{x}\)(x khác 0)

\(\dfrac{x+2}{7}\)=\(\dfrac{-36}{28}\)

tìm x: