Bài 2:
a: \(x:1\dfrac{2}{7}=-3,5\)
=>\(x:\dfrac{9}{7}=-\dfrac{7}{2}\)
=>\(x=-\dfrac{7}{2}\cdot\dfrac{9}{7}=-\dfrac{9}{2}\)
b: \(0,4x-\dfrac{1}{5}x=\dfrac{3}{4}\)
=>\(x\left(0,4-0,2\right)=\dfrac{3}{4}\)
=>\(x\cdot\dfrac{1}{5}=\dfrac{3}{4}\)
=>\(x=\dfrac{3}{4}:\dfrac{1}{5}=\dfrac{3}{4}\cdot5=\dfrac{15}{4}\)
Bài 1:
a: \(\left(\dfrac{7}{3}+3,5\right):\left(-\dfrac{25}{6}+\dfrac{22}{7}\right)+0,5\)
\(=\left(\dfrac{7}{3}+\dfrac{7}{2}\right):\left(-\dfrac{175}{42}+\dfrac{132}{42}\right)+\dfrac{1}{2}\)
\(=\dfrac{35}{6}:\dfrac{-43}{42}+\dfrac{1}{2}\)
\(=\dfrac{35}{6}\cdot\dfrac{42}{-43}+\dfrac{1}{2}=\dfrac{35\cdot7}{-43}+\dfrac{1}{2}=\dfrac{-447}{86}\)
b: \(\dfrac{38}{7}+\left(-3,25\right)-\dfrac{17}{7}+4,55\)
\(=\left(\dfrac{38}{7}-\dfrac{17}{7}\right)+\left(4,55-3,25\right)\)
\(=\dfrac{21}{7}+1,3=3+1,3=4,3\)