x-(57-(42+(-23-x)=13-47+25-23-x

 x-57-42-23-x=13-47+25-23-x

 x-122-x=-32-x

 x-x-122=-32-x

 -32-x=-122

        x=-32-(-122)

        x=90

 Vậy x=90

\(x-(57-(42+(-23-x)=13-47+25-13-x\)

\(\Rightarrow x-57-42+\left(-23\right)-x=13-47+25-23-x\)

\(\Rightarrow x-x+x=13-47+25-23+23+42+57\)

\(\Rightarrow x=90\)

\(a.\dfrac{12+x}{42}=\dfrac{35}{42}\Leftrightarrow12+x=35\Leftrightarrow x=23\)

\(b.\dfrac{25-x}{40}=\dfrac{3}{8}\Leftrightarrow\dfrac{25-x}{40}=\dfrac{15}{40}\Leftrightarrow25-x=15\Leftrightarrow x=10\)

\(c.\dfrac{13+x}{20}=\dfrac{3}{4}\Leftrightarrow\dfrac{13+x}{20}=\dfrac{15}{20}\Leftrightarrow13+x=15\Leftrightarrow x=2\)

\(d.\dfrac{23-x}{25}=\dfrac{20}{25}\Leftrightarrow23-x=20\Leftrightarrow x=3\)

a: =>x-15=20

hay x=35

c: =>12x=360

hay x=30

9700 : 100 + 36 x 12 = 529

(160 x 5 - 25 x 4) : 4= 175

108 x (23 + 7) = 3240

215 x 86 + 215 x 14 = 21500

3 x 128 - 43 x 128= -5120

529

175

3240

21500

-5120 (lớp 4 học âm hẻ)

529

175

3240

21500

....

a,\(\frac{1}{5}\times\frac{2}{9}\div\frac{1}{15}\)

\(=\frac{1}{5}\times\frac{2}{9}\times15\)

\(=\left(\frac{1}{5}\times15\right)\times\frac{2}{9}\)

\(=3\times\frac{2}{9}\)

\(=\frac{2}{3}\)

b\(\frac{4}{15}\times\frac{7}{15}\times\frac{5}{4}\)

\(=\left(\frac{4}{15}\times\frac{5}{4}\right)\times\frac{7}{15}\)

\(=\frac{1}{3}\times\frac{7}{15}\)

\(=\frac{7}{45}\)

c,\(\frac{21}{23}\times\frac{5}{11}\times\frac{44}{?}\)

d,\(26\times\frac{13}{42}\div13\)

\(=\left(26\div13\right)\times\frac{13}{42}\)

\(=2\times\frac{13}{42}\)

\(=\frac{13}{21}\)

ờ ờ .......................... hong bt

21/23 x 5/11x 44/35

a)=>x=13+3/5=68/5.

Vậy x = 68/5

b)=>x/6=5/7+-23/42

=>x/6=1/6

=>x=1

Vậy x=1

còn lại tự làm nha😆😆😆😆😆

a) x-3/5=13

suy ra x=13+3/5

suy ra x=68/5

suy ra x=13.6

b)x/6=5/7+23/-42

suy ra x/6=1/6

suy ra x=1

d) x+11/12=2/5

suy ra x=2/5-11/12

suy ra x=-31/60

\(x-\left\{57-\left[42+\left(-23-x\right)\right]\right\}=13-\left\{47+\left[25-\left(32-x\right)\right]\right\}\)

=>\(x-\left\{57-42+23+x\right\}=13-47-25+32-x\)

=>\(x-\left(x+38\right)=-27-x\)

=>\(-27-x=-38\)

=>x+27=38

=>\(x=38-27=11\)

\(x-\left\{57-\left[42+\left(-23-x\right)\right]\right\}=13-\left\{47+\left[25-\left(32-x\right)\right]\right\}\)

\(\Leftrightarrow x-57+42-23-x=13-47-25+32-x\)

\(\Leftrightarrow x-x-57+42-23=-27-x\)

\(\Leftrightarrow-57+42-23=-27-x\)

\(\Leftrightarrow-38=-27-x\)

\(\Leftrightarrow x=\left(-27\right)-\left(-38\right)\)

\(\Leftrightarrow x=11\)

Vậy \(x=11\) là giá trị cần tìm

\(x-\left(57-\left(42+\left(-23-x\right)\right)\right)=13-\left(47+\left(25-\left(32-x\right)\right)\right)\)

\(\Leftrightarrow\) \(x-\left(57-\left(42-23-x\right)\right)=13-\left(47+\left(25-32+x\right)\right)\)

\(\Leftrightarrow\) \(x-\left(57-42+23+x\right)=13-\left(47+25-32+x\right)\)

\(\Leftrightarrow\) \(x-57+42-23-x=13-47-25+32-x\)

\(\Leftrightarrow\) \(-38=-27-x\) \(\Leftrightarrow\) \(-x=-38+27=-11\Leftrightarrow x=11\)

vậy \(x=11\)