Bài $1$ :
`-21.(37-53)+53.(37-21)`
`=(-21).(-16)+53.16`
`=336+848`
`=1184`
Bài $2$ :
`a)(2x)/3=(-6)/(y+2)=4/6`
$\left[ \begin{array}{l}\dfrac{2}{3}=\dfrac{2x}{3}\\\dfrac{2}{3}=\dfrac{-6}{y+2}\end{array} \right.$
$\left[ \begin{array}{l}x=1\\x=-11\end{array} \right.$
`b)2x+11=3.(x+15)`
`<=>2x+11=3x+45`
`<=>2x+11-11=3x+45-11`
`<=>2x=3x+34`
`<=>2x-3x=3x+34-3x`
`<=>-x=34`
`<=>x=-34`
