`12(x+9)(x-3)(2x-4)=0`

`=>` \(\left[{}\begin{matrix}x+9=0\\x-3=0\\2x-4=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0-9\\x=0+3\\2x=4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-9\\x=3\\x=2\end{matrix}\right.\)

Vậy `S = {-9;3;2}`

`(3x-4).(4-5x)=0`

`=>` \(\left[{}\begin{matrix}3x-4=0\\4-5x=0\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}3x=4\\5x=4\end{matrix}\right.\)

`=>` \(\left[{}\begin{matrix}x=4:3=\dfrac{4}{3}\\x=4:5=\dfrac{4}{5}\end{matrix}\right.\)

Vậy `S = {4/3; 4/5}`

Số cây cam có :

`36 xx 1/3 =12(cây)`

`10/3 - 8/3 =(10-8)/3 = 2/3`

`8/11 - 4/11 = (8-4)/11 = 4/11`

`4/18 - 1/9 = 2/9 - 1/9 =(2-1)/9 = 1/9`

`19/5 - 3/15 = 19/5 - 1/5 = (19-1)/5 = 18/5`

`3-16/11 = 33/11 - 16/11= (33-16)/11 = 17/11`

`9/8-1=9/8-8/8=(9-8)/8 = 1/8`

`x-15=17-48`

`x-15=-31`

`x=-31+15`

`x=-16`

____________________

`x-21=(-7)-4`

`x-21=-7-4`

`x-21=-11`

`x=-11+21`

`x=10`

______________________

`x-12=(-9)-15`

`x-12=-9+15`

`x-12=-24`

`x=-24+12`

`x=-12`

`4/5 + 3/4 = 16/20 + 15/20 = (16+15)/20= 31/20`

`8/3 + 10/7 = 56/21 + 30/21 = (56+30)/21 = 86/21`

`9/5 + 5/8 = 72/40 + 25/40 = (72+25)/40 = 97/40`

`3/5 + 13/9 = 27/45 + 65/45 = (27+65)/45 = 92/45`

`2/3 + 11/2 = 4/6 + 33/6 = (4+33)/6 = 37/6`

`9/4 + 17/20 = 45/20 + 17/20 = (45+17)/20 = 62/20 = 31/10`

`43/6 + 45/8 = 172/24 + 135/24 = (172+135)/24 = 307/24`

`5/9 + 7/15 = 25/45 + 21/45 = (25+21)/45 = 46/45`

`3-x=-21-(-9)`

`3-x=-21+9`

`3-x=-12`

`x=3-(-12)`

`x=3+12`

`x=15`

_______________

`-12-x-(-19)=0`

`-12-x+19=0`

`-12-x=0-19`

`-12-x=-19`

`x=-12-(-19)`

`x=-12+19`

`x=7`

________________________

`46-x=-21+(-87)`

`46-x=-21-87`

`46-x=-108`

`x=46-(-108)`

`x=46+108`

`x=154`

`25 xx 0,5 xx 4 xx 2 xx 71 xx8 xx 125`

`=(25 xx 4) xx ( 8 xx 125) xx (0,5 xx 2) xx 71`

`=100 xx ( 8 xx 125) xx (0,5 xx 2) xx 71`

`=100 xx 1000 xx 1 xx 71`

`=100000 xx 71`

`=7100000`

Tỉ số tiền của An và Bình :

`3/5:2/3 = 9/10`

Tổng số phần bằng nhau :

`9+10=19(phần)`

An có số tiền :

`38000 : 19 xx 9 = 18000(đồng)`

Bình có số tiền :

`38000 - 18000 = 20000(đồng)`

Đ/s..

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