Bài 10:

a: x-5=-1

=>x=-1+5

=>x=4

b: x+30=-4

=>x=-4-30

=>x=-34

c: x-(-24)=3

=>x+24=3

=>x=3-24

=>x=-21

d: 22-(-x)=12

=>22+x=12

=>x=12-22

=>x=-10

e: (x+5)+(x-9)=x+2

=>x+5+x-9=x+2

=>2x-4=x+2

=>2x-x=4+2

=>x=6

f: (27-x)+(15+x)=x-24

=>x-24=27-x+15+x=42

=>x=42+24

=>x=66

Bài 9:

a: 15-(4-x)=6

=>4-x=15-6=9

=>x=4-9=-5

b: -30+(25-x)=-1

=>-30+25-x=-1

=>-5-x=-1

=>x+5=1

=>x=1-5

=>x=-4

c: x-(12-25)=-8

=>x-(-13)=-8

=>x+13=-8

=>x=-8-13

=>x=-21

d: (x-29)-(17-38)=-9

=>x-29-(-21)=-9

=>x-29+21=-9

=>x-8=-9

=>x=-9+8

=>x=-1

Bài 8:

a: (17-229)+(17-25+229)

=17-229+17-25+229

=34-25

=9

b: (125-679+145)-(125-679)

=125-679+145-125+679

=145

a, 15 - ( 4 - x ) = 6

⇒ 15 - 4 + x = 6

⇒ 11+ x = 6

⇒ x = -5

 c, x - ( 12 - 25 ) = -8

⇒ x + 13 = -8

⇒ x = -21

d, ( x - 29 ) - ( 17 - 38 ) = -9

⇒ x - 29 + 21 = -9

⇒ x - 8 = -9

⇒ x = -1

b, - 30 + ( 25 - x ) = -1

⇒ - 30 + 25 - x = -1

⇒ -5 - x = -1

⇒ x = -4

a, \(15-4+x=6\) ⇒ \(11-x=6\) ⇒ \(x=5\)

b, \(-30+25-x=-1\) ⇒ \(-5-x=-1\) ⇒ \(x=-4\)

c, \(x-12+25=-8\Rightarrow x+13=-8\) ⇒ \(x=-21\)

d, \(x-29-17+38=-9\Rightarrow x-8=-9\Rightarrow x=-1\)

-25-x-61=95-25-61

-25-x-61=9

X-61=-25-9

x-61=-34

x=-34+61

x=27

-25-x-61=95-25-61

-25-x-61=9

      x-61=-25-9

      x-61=-34

           x=-34+61

           x=27

tìm x

a.9/25-12/25:x=1/5

12/25:x=9/25 - 1/5

12/25:x=4/25

x=12/25 : 4/25

x=1/3

b.8/17*x+2/9=10/27

8/17*x=10/27 - 2/9

8/17*x=4/27

x=4/27 : 8/17

x=17/45

a: =>12/25:x=9/25-1/5=4/25

=>x=3

b: =>8/17x=10/27-2/9=10/27-6/27=4/27

hay x=17/54

a) x - (17 - 8) = 5 + (10 - 3x)

x - 17 + 8 = 5 + 10 - 3x

x + 3x = 5 + 10 + 17 - 8

4x = 24

x = 24 : 4

x = 6

b) 25 - (30 + x) = x - (27 - 8)

25 - 30 - x = x - 27 + 8

-x - x = -27 + 8 - 25 + 30

-2x = -14

x = (-14) : (-2)

x = 7

c) (x - 12) - 15 = (20 - 7) - (18 + x)

x - 12 - 15 = 20 - 7 -18 - x

x + x = 20 - 7 - 18 + 12 + 15

2x = 22

x = 22 : 2

x = 11

d) 9 - 25 = (7 - x) - (25 + 7)

9 - 25 = 7 - x - 25 - 7

x = 7 - 25 - 7 - 9 +25

x = -9

\(1/\)

\(\frac{12}{49}:\frac{16}{21}\)

\(=\frac{12}{49}\times\frac{21}{16}\)

\(=\frac{12\times21}{49\times16}\)

\(=\frac{252}{784}=\frac{9}{28}\)

\(2/\)

\(a,\frac{5}{11}-\left(\frac{39}{61}+\frac{12}{61}\right)\)

\(=\frac{5}{11}-\frac{51}{61}\)

\(=-\frac{256}{671}\)

\(b,\frac{17}{12}+\frac{9}{7}-\left(\frac{2}{7}-\frac{7}{12}\right)\)

\(=\frac{17}{12}+\frac{9}{7}-\frac{2}{7}+\frac{7}{12}\)

\(=\left(\frac{17}{12}+\frac{7}{12}\right)+\left(\frac{9}{7}-\frac{2}{7}\right)\)

\(=2+1\)

\(=3\)

\(c,\frac{16}{17}\times\frac{12}{19}+\frac{16}{17}\times\frac{7}{19}\)

\(=\frac{16}{17}\times\left(\frac{12}{19}+\frac{7}{19}\right)\)

\(=\frac{16}{17}\times1\)

\(=\frac{16}{17}\)

\(3/\)

\(a,x:\frac{4}{5}=\frac{25}{8}:\frac{5}{4}\)

\(x:\frac{4}{5}=\frac{5}{2}\)

\(x=2\)

\(b,\frac{22}{5}:x=\frac{44}{5}:\frac{5}{2}\)

\(\frac{22}{5}:x=\frac{88}{25}\)

\(x=\frac{5}{4}\)

\(c,x\times\frac{4}{9}\times\frac{15}{18}=\frac{25}{18}\)

\(x\times\frac{4}{9}=\frac{5}{3}\)

\(x=\frac{15}{4}\)

mọi người giúp mk với, mk đang cần gấp

Thay x = -98, a = 61 vào biểu thức ta được:

-(-98) – 61 + 12 + 61 = 98 + (-61) + 12 + 61

= (98 + 12) + [(-61) + 61] = 110 + 0 = 110