Bài 1:
1) \(7\dfrac{2}{8}-\left(2\dfrac{3}{5}+4\dfrac{3}{38}\right)\)
\(=\dfrac{29}{4}-\left(\dfrac{13}{5}+\dfrac{155}{38}\right)\)
\(=\dfrac{29}{4}-\dfrac{1269}{190}\)
\(=\dfrac{217}{380}\)
2) \(\left(13\dfrac{3}{5}+4\dfrac{3}{4}\right)-8\dfrac{3}{5}\)
\(=\left(\dfrac{68}{5}+\dfrac{19}{4}\right)-\dfrac{43}{5}\)
\(=\dfrac{367}{20}-\dfrac{43}{5}\)
\(=\dfrac{39}{4}\)
3) \(\left[\left(6\dfrac{3}{5}-3\dfrac{3}{14}\right).5\dfrac{5}{6}\right]:\left[\left(21-1\dfrac{1}{4}\right):2\dfrac{1}{2}\right]\)
\(=\left[\left(\dfrac{33}{5}-\dfrac{45}{14}\right).\dfrac{35}{6}\right]:\left[\left(21-\dfrac{5}{4}\right):\dfrac{5}{2}\right]\)
\(=\left(\dfrac{237}{70}.\dfrac{35}{6}\right):\left(\dfrac{79}{4}.\dfrac{2}{5}\right)\)
\(=\dfrac{79}{4}:\dfrac{79}{10}\)
\(=\dfrac{5}{2}\)
Bài 2:
1) \(\dfrac{x}{150}=\dfrac{5}{6}.\left(-\dfrac{7}{25}\right)\)
\(\dfrac{x}{150}=-\dfrac{7}{30}\)
\(x=-35\)
Vậy x=-35
2) \(1-\left(5\dfrac{3}{8}-x-7\dfrac{5}{24}\right):16\dfrac{2}{3}=0\)
\(1-\left(\dfrac{43}{8}-x-\dfrac{173}{24}\right):\dfrac{50}{3}=0\)
\(1-\left(-\dfrac{11}{6}-x\right).\dfrac{3}{50}=0\)
\(1+\dfrac{11}{100}+\dfrac{3}{50}x=0\)
\(\dfrac{3}{50}x+\dfrac{111}{100}=0\)
\(\dfrac{3}{50}x=-\dfrac{111}{100}\)
\(x=-\dfrac{37}{2}\)
Vậy x= \(\dfrac{-37}{2}\)