Bài 1 :
`a,|-30|+(-40)-(-20)`
`=30-40+20`
`=10`
`b,8(-2)+(-52):(-13)+|-16|`
`=-16+4+16`
`=(-16+16)+4`
`=0+4`
`=4`
`c,49(-25)+51(-25)`
`=-25(49+51)`
`=-25.100`
`=-2500`
`d,60:(-20)+(4-6)³+|-23|`
`=-3-8+23`
`=12`
Bài 2 :
`a,x-24=-20`
`=>x=-20+24`
`=>x=4`
`b,-18+2x=-30`
`=>2x=-30+18`
`=>2x=-12`
`=>x=-12:2`
`=>x=-6`
`c,(27-x)(-2)=-40`
`=>27-x=(-40):(-2)`
`=>27-x=20`
`=>x=27-20`
`=>x=7`
`d,|-x+15|=35`
`⇒`\(\left[ \begin{array}{l}-x+15=35\\-x+15=-35\end{array} \right.\)
`⇒`\(\left[ \begin{array}{l}x=-20\\x=50\end{array} \right.\)
Bài 4 :
`-3 \vdots n+5`
`=>n+5∈Ư(-3)`
`=>n+5∈{-3,-1,1,3}`
`=>n∈{-8,-6,-4,-2}`
Xin hay nhất !
