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\(\left(x+15\right):3=7\)
\(x+15=7.3\)
\(x+15=21\)
\(x=21-15\)
\(x=6\)
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\(4.\left(6-x\right)=280:36\)
\(4.\left(6-x\right)=\dfrac{70}{9}\)
\(6-x=\dfrac{70}{9}:4\)
\(6-x=\dfrac{35}{18}\)
\(x=6-\dfrac{35}{18}\)
\(x=\dfrac{73}{18}\)
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\(5x-3x-12=8\)
\(2x=8+12\)
\(2x=20\)
\(x=\dfrac{20}{2}\)
\(x=10\)
\(\left(x+15\right):3=7\\ \Rightarrow x+15=7.3=21\\ \Rightarrow x=21-15=6\)
\(4\left(6-x\right)=280:36\\ \Rightarrow4\left(6-x\right)=\dfrac{70}{9}\\ \Rightarrow6-x=\dfrac{70}{9}:4\\ \Rightarrow6-x=\dfrac{35}{18}\\ \Rightarrow x=6-\dfrac{35}{18}=\dfrac{73}{18}\)
\(5x-3x-12=8\\ \Rightarrow2x=8+12=20\\ \Rightarrow x=\dfrac{20}{2}=10\)

\(\left(x+2\right)-2=0\)
\(\Rightarrow x+2-2=0\)
\(\Rightarrow x=0\)
\(\left(x+3\right)+1=7\)
\(\Rightarrow x+3+1=7\)
\(\Rightarrow x+4=7\)
\(\Rightarrow x=3\)
\(\left(3x-4\right)+4=12\)
\(\Rightarrow3x-4+4=12\)
\(\Rightarrow3x=12\)
\(\Rightarrow x=4\)
\(\left(5x+4\right)-1=13\)
\(\Rightarrow5x+4-1=13\)
\(\Rightarrow5x+3=13\)
\(\Rightarrow5x=10\)
\(\Rightarrow x=2\)
\(\left(4x-8\right)-3=5\)
\(\Rightarrow4x-8-3=5\)
\(\Rightarrow4x-11=5\)
\(\Rightarrow4x=16\)
\(\Rightarrow x=4\)
\(8-\left(2x+4\right)=2\)
\(\Rightarrow8-2x-4=2\)
\(\Rightarrow4-2x=2\)
\(\Rightarrow2x=2\)
\(\Rightarrow x=1\)
\(7+\left(5x+2\right)=14\)
\(\Rightarrow7+5x+2=14\)
\(\Rightarrow9+5x=14\)
\(\Rightarrow5x=5\)
\(\Rightarrow x=1\)
\(5-\left(3x-11\right)=1\)
\(\Rightarrow5-3x+11=1\)
\(\Rightarrow16-3x=1\)
\(\Rightarrow3x=15\)
\(\Rightarrow x=5\)

1) -3-(-x) =5
=> -3 + x = 5
=> x = 5 - (-3)
=> x = 8
2)-9-(x-3)=12
=> x- 3 = (-9) - 12
=> x-3 =-21
=> x = (-21)+3
=> x = -18
3)-10-(x-5)=-5
x-5 = (-10) -(-5)
x-5 = -5
x = -5 +5
x = 0
4)210-(10-x) =110
10-x = 210 -110
10-x = 100
x = 10 -100
x = -90
5)4x-(2x-5)=21
=> 4x-2x + 5 =21
=> x(4-2) + 5 = 21
=> x.2 =21 - 5
=> x.2 = 16
=> x = 16:2
=> x = 8
6)14x-5=8x+10
7)15+5x =3x+30
8)2x-5=15-3x
9)2(3x+5)+3(x+1)=x+220
10)4.(x-2+5(x-3)=18

\(\left(x+15\right):3=7\)
\(x+15=7.3\)
\(x+15=21\)
\(x=21-15\)
\(x=6\)
_____
\(5x-3x-12=8\)
\(\Leftrightarrow2x-12=8\)
\(2x=8+12\)
\(2x=20\)
\(x=20:2\)
\(x=10\)
______
\(4.\left(6-x\right)=280:36\)
\(4.\left(6-x\right)=\dfrac{280}{36}\)
\(6-x=\dfrac{280}{36}.\dfrac{1}{4}\)
\(6-x=\dfrac{35}{18}\)
\(x=6-\dfrac{35}{18}\)
\(x=\dfrac{108}{18}-\dfrac{36}{18}\)
\(x=\dfrac{73}{18}\)
\(\frac{12}{15}-3x=\frac{1}{5}x\)
\(\frac{12}{15}=\frac{1}{5}x+3x\)
\(\frac{12}{15}=\frac{16}{5}x\)
\(\frac{12}{15}:\frac{16}{5}=x\)
\(x=\frac{1}{4}\)
ủng hộ nhé
=>4/5=16/5x=>x=16/5:4/5=>x=4