ừ thế đấy

\(c\)) \(\left(\dfrac{21}{31}+\dfrac{2013}{6039}\right)-\left(\dfrac{44}{53}-\dfrac{10}{31}\right)-\dfrac{9}{53}\)

\(=\left(\dfrac{21}{31}+\dfrac{1}{3}\right)-\left(\dfrac{44}{53}-\dfrac{10}{31}\right)-\dfrac{9}{53}\)

\(=\)_______________________\(\left(\text{sory tớ ko làm đc nữa}\right)\)

\(b\)) \(\dfrac{-7}{9}.\dfrac{4}{11}+\dfrac{-7}{9}.\dfrac{7}{11}+\dfrac{52}{9}\)

\(=\dfrac{-7}{9}.\left(\dfrac{4}{11}+\dfrac{7}{11}\right)+\dfrac{52}{9}\)

\(=\dfrac{-7}{9}.1+\dfrac{52}{9}\)

\(=\dfrac{-7}{9}+\dfrac{52}{9}=5\)

\(a\)) \(\dfrac{-3}{4}+\dfrac{3}{7}+\dfrac{-1}{4}+\dfrac{4}{9}+\dfrac{4}{7}\)

\(=\left(\dfrac{-3}{4}+\dfrac{-1}{4}\right)+\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\dfrac{4}{9}\)

\(=-1+1+\dfrac{4}{9}\)

\(=0+\dfrac{4}{9}=\dfrac{4}{9}\)

\(\text{Tìm x, biết:}\)

\(20\text{%}x-x+\dfrac{1}{5}=\dfrac{3}{4}\)

ừ thế đấy