`a)[2x]/[-9]=10/91`

`=>2x.91=10.(-9)`

`=>182x=-90`

`=>x=-90/182`

`=>x=-45/91`

\(\Rightarrow2x\times91=10\times\left(-9\right)\\ \Rightarrow2x=\dfrac{-90}{91}\\ \Rightarrow x=\dfrac{-90}{91}:2\\ \Rightarrow x=-\dfrac{45}{91}\)

\(\dfrac{-1}{9}.\dfrac{3}{5}+\dfrac{-1}{4}.\dfrac{-4}{5}+\dfrac{1}{9}.\dfrac{2}{5}\)

\(\text{=}\dfrac{-1}{15}+\dfrac{1}{5}+\dfrac{2}{45}\)

\(\text{=}\dfrac{8}{45}\)

Áp dụng tính chất đổi dấu và giao hoán của phép nhân phân số, ta có:

\(\dfrac{-1}{9}.\dfrac{3}{5}+\dfrac{-1}{4}.\dfrac{-4}{5}+\dfrac{1}{9}.\dfrac{2}{5}=\dfrac{1}{5}.\dfrac{-3}{9}+\dfrac{1}{5}.\dfrac{4}{4}+\dfrac{1}{5}.\dfrac{2}{9}\)

                                           \(=\dfrac{1}{5}\left(-\dfrac{3}{9}+1+\dfrac{2}{9}\right)\)

                                           \(=\dfrac{1}{5}\left(-\dfrac{3}{9}+\dfrac{9}{9}+\dfrac{2}{9}\right)\)

                                           \(=\dfrac{1}{5}.\dfrac{8}{9}\)

                                           \(=\dfrac{8}{45}\)

\(\dfrac{5}{9}+\dfrac{-x}{6}\text{=}\dfrac{-1}{3}\)

\(\dfrac{10}{18}+\dfrac{-3x}{18}\text{=}\dfrac{-6}{18}\)

\(10-3x\text{=}-6\)

\(-3x\text{=}-6-10\)

\(-3x\text{=}-16\)

\(x\text{=}\dfrac{16}{3}\)

`x+3/2=-12-6`

`=> x+3/2=-18`

`=> x=-18-3/2`

`=> x=-36/2-3/2`

`=> x=-39/2`

\(x+\dfrac{3}{2}\text{=}-12-6\)

\(x+\dfrac{3}{2}\text{=}-18\)

\(x\text{=}-18-\dfrac{3}{2}\)

\(x\text{=}\dfrac{-39}{2}\)

Ai giúp với

17,588m vải

-1/2 

`46,8xx7,4-18:1,5`

`=346,32-12`

`=334,32`

\(46,8\cdot7,4-18:1,5\)
\(=346,32-12=334,32\)