\(a,\dfrac{x+81}{19}+\dfrac{x+82}{18}=\dfrac{x+84}{16}+\dfrac{x+85}{15}\)

\(b,\dfrac{x+7}{3}+\dfrac{x+5}{4}=\dfrac{x+3}{5}+\dfrac{x+1}{6}\)

\(a,\dfrac{4}{3}.x=\dfrac{-2}{5}\)

\(b,x.\dfrac{3}{7}=\dfrac{-21}{5}\)

\(c,\dfrac{3}{4}:x=\dfrac{-7}{6}\)

\(d,\dfrac{-1}{3}:x=\dfrac{-2}{3}\)

\(e,\dfrac{4}{9}+\dfrac{5}{6}:x=\dfrac{1}{6}\)

\(f,\dfrac{5}{4}:x+2=\dfrac{2}{3}\)

\(\dfrac{4}{5}+\dfrac{7}{6}:x=\dfrac{1}{6}\)

chứng minh

\(\dfrac{1}{10}+\dfrac{1}{11}+\dfrac{1}{12}+...+\dfrac{1}{18}+\dfrac{1}{19}< 1\)

\(\dfrac{5}{6}-x=\dfrac{-2}{3}\)