a)

     \(25\times189-25\times88-25\)

\(=25\times\left(189-88-1\right)\)

\(=25\times100\)

\(=2500\)

b)

     \(38\times66-38\times56+62\times65-62\times55\)

\(=38\times\left(66-56\right)+62\times\left(65-55\right)\)

\(=38\times10+62\times10\)

\(=10\times\left(38+62\right)\)

\(=10\times100\)

\(=1000\)

c)

    \(29\times69+29\times31-23\times100\)

\(=29\times\left(69+31\right)-23\times100\)

\(=29\times100-23\times100\)

\(=100\times\left(29-23\right)\)

\(=100\times6\)

\(=600\)

d)

    \(\left(519\times288-516\times288\right)\div288\)

\(=288\times\left(519-516\right)\div288\)

\(=288\times3\div288\)

\(=3\)

a)

     $25\times 189-25\times 88-25$

$=25\times \left(189-88-1\right)$

$=25\times 100$

$=2500$

b)

     $38\times 66-38\times 56+62\times 65-62\times 55$

$=38\times \left(66-56\right)+62\times \left(65-55\right)$

$=38\times 10+62\times 10$

$=10\times \left(38+62\right)$

$=10\times 100$

$=1000$

c)

    $29\times 69+29\times 31-23\times 100$

$=29\times \left(69+31\right)-23\times 100$

$=29\times 100-23\times 100$

$=100\times \left(29-23\right)$

$=100\times 6$

$=600$

d)

    $\left(519\times 288-516\times 288\right)÷288$

$=288\times \left(519-516\right)÷288$

$=288\times 3÷288$

$=3$

a) 31 . { 330 : [178 – 4 . ( 35 – 21 : 3 )]} = 31 . { 330 : [178 – 4 . ( 35 – 7)]}

= 31 . { 330 : [178 – 4 . 28]} = 31 . { 330 : [178 – 112]}

= 31 . { 330 : 66 } = 31 . 5 = 155

( 5 19 .  5 14 ) :  5 32 =  5 33 :  5 32  = 5

a) 31 . { 330 : [178 – 4 . ( 35 – 21 : 3 )]} = 31 . { 330 : [178 – 4 . ( 35 – 7)]}

= 31 . { 330 : [178 – 4 . 28]} = 31 . { 330 : [178 – 112]}

= 31 . { 330 : 66 } = 31 . 5 = 155

b) ( 5 19  .  5 14 ) :  5 32  =  5 33 :  5 32 = 5

A=15/8              D=27/40

B=4/15              E=1/14        

C=7/3                F=637/48

a) ( 2011 - 125 x 8 : 4 ) x ( ( 48 : 8 x 6 )

= ( 2011 - 1000 : 4 ) x ( 6 x 6 )

= ( 2011 - 250 ) x 36

= 1761 x 36

= 63396

b) B = Không hiểu

c) C = 

a) Ta có: a = -1/8 = -9/72

b = 2/-9 = -2/9 = -16/72

Ta thấy: -9 > -16 => -9/72 > -16/72

hay a > b

Vậy a > b

b) Ta có: a = 12/15 = 4/5= 16/20

b = -( -3/4 ) = 3/4= 15/20

Ta thấy: 16 > 15 => 16/20 > 15/20

hay a > b

Vậy a > b

c) Ta có: a = -2/3 = -40/60

b = -0,65 = -13/20 = -39/60

Ta thấy: -40 < -39 => -40/60 < -39/60

hay a < b

Vậy a < b

d) Ta có:  a = -21/3 = -7

b = -413% = -4,13

Ta thấy: -7 < -4,13

=> a < b

Vậy a < b

Chuk bn hok tốt!