\(200:25-\left(12-x\right)=4\\ 8-\left(12-x\right)=4\\ 12-x=8-4\\ 12-x=4\\ x=12-4\\ x=8\\ ---\\ \left(x-10\right).5=100-20.4\\ \left(x-10\right).5=100-80=20\\ x-10=\dfrac{20}{5}=4\\ x=4+10=14\)

a)\(200:25-\left(12-x\right)=4\)

\(\Rightarrow8-\left(12-x\right)=4\)

\(\Rightarrow12-x=8-4\)

\(\Rightarrow12-x=4\)

\(\Rightarrow x=12-4\)

\(\Rightarrow x=8\)

b) \(\left(x-10\right)\cdot5=100-20\cdot4\)

\(\Rightarrow\left(x-10\right)\cdot5=100-80\)

\(\Rightarrow\left(x-10\right)\cdot5=20\)

\(\Rightarrow x-10=4\)

\(\Rightarrow x=10+4\)

\(\Rightarrow x=14\)

100 x 200 = 20000

10 x 10 = 100

200 x 10 = 2000

1000 x 25 = 25000

K mình nha xin bạn đó mình đang bị âm điểm !!!

= 20000

= 100

= 2000

= 25000

^ ^ 

c, 200 - ( 2x + 6 ) = 4 ^ 3

   200 - ( 2x + 6 ) = 64

             2x + 6   = 200 - 64

             2x + 6   = 136

             2x    =   136 - 6

             2x = 130

             x = 130 : 2 

             x = 65

a, 25 + 3 ( x - 8 ) = 106 

3( x - 8 ) = 106 - 25

3( x - 8 ) = 81

   x - 8 = 81 : 3

   x - 8 = 27

x = 27 + 8 

x = 35 .

7 × 3 mu x + 20 × 3 mu x = 3 mu 25

=100+100+1000

=1200

1200 à? Mik tính nhẩm đó

a) 125 x 45 + 45 x 25 + 90 x 25

  =125 x 45 + 45 x 25 + 2 x 45 x 25

  =45 x [125 + 25 + ( 2 x 25 )]

  =45 x [125 + 25 + 50]

  =45 x 200

  = 9000

c) 25 x 20 x 4 - 200 x 40

  =25 x 2 x 10 x 4 - 200 x 40

  =(25 x 2 x 4) x 10 - 200 x 40

  =200 x 10 - 200 x 40

  =200 x (10 - 40)

  =200 x (-30)

  = -6000

Phần a bạn đúng rồi còn phần c sai rồi

`a)25xx532xx4`

`=(25xx4)xx432`

`=432xx100=43200`

`b)456xx200-456xx100`

`=456xx(200-100)`

`=456xx100=45600`

\(a,25\times432\times4=25\times4\times432=100\times432=4320\\ b,456\times200-456\times100=456\times\left(200-100\right)=456\times100=45600\)

\(x-4\times25\%+10=200\)

\(=x-1+10=200\)

\(x-1=200-10\)

\(x-1=190\)

\(x=190+1\)

\(x=191\)