a,24.57+43.24

=24.(57+43)

=24.100

=2400

b,12.19+12

=12.(19+1)

=12.20

=12.10.2

=120.2

=240

c,43.27+93.43+57.61+59.57

=43.(27+93)+57.(61+59)

=43.120+57.120

=120.(43+57)

=120.100

=12000

d,64.6+81.4+17.6

=64.6+27.3.2.2+17.6

=64.6+54.6+17.6

=(64+54+17).6

=135.6

=810

a) 24 . 57 + 43 . 24

= 24 . (57 + 43)

= 24 . 100

= 2400

b) 12 . 19 + 12

= 12 . (19 + 1)

= 12 . 20

=240

c) 43 . 27 + 93 . 43 + 57 . 61 +59 . 57

= 43 . ( 27 + 93) + 57 . (61 + 59)

= 43 . 120 + 57 . 120

= 120 . (43 + 57)

= 120 . 100

= 12000

\(a,24\cdot57+43\cdot24\)

\(=24\cdot\left(57+43\right)\)

\(=24\cdot100=2400\)

\(b,12\cdot19+12\)

\(=12\cdot\left(19+1\right)\)

\(=12\cdot20=240\)

\(c,43\cdot27+93\cdot42+57\cdot61+59\cdot57\)

\(=43\cdot\left(27+93\right)+57\cdot\left(61+59\right)\)

\(=43\cdot120+57\cdot120\)

\(= \left(43+57\right)\cdot120\)

\(=100\cdot120=12000\)

\(d,64\cdot6+81\cdot4+17\cdot6\)

\(=\left(64+17\right)\cdot6+81\cdot4\)

\(=81\cdot6+81\cdot4\)

\(=81\cdot\left(6+4\right)\)

\(=81\cdot10=810\)

Có nên giúp ko ta

\(a,\left(13+150+47\right)-\left(13+47\right)\)

\(=13+150+47-13-47\)

\(=\left[13+\left(-13\right)\right]+\left[47+\left(-47\right)\right]+150\)

\(=0+0+150\)

\(=150\)

\(b,\left(-237\right)-\left[\left(-237+155\right)-55\right]\)

\(=\left(-237\right)+237+155-55\)

\(=0+100\)

\(=100\)

\(c,57.\left(62-43\right)-62.\left(57-43\right)\)

\(=57.62-57.43-62.57+62.43\)

\(=-57.43+62.43\)

\(=43.\left(-57+62\right)\)

\(=43.5\)

\(=215\)

a , ( 13 + 150 + 47 ) - ( 13 + 47 )

= 12 + 150 + 47 - 13 - 47

= [ 12 + ( - 13 ) ] + [ 47 + ( - 47 ) ] + 150

= - 1 + 0 + 150

= 149

b , ( - 237 ) - [ ( - 237 + 155 ) - 55 ]

= - 237 - [ - 237 + 155 - 55 ]

= - 237 + 237 - 155 + 55

= [ ( - 237 ) + 237 ] + [ ( - 155 ) + 55 ]

= 0 +  ( - 100 )

= - 100

c , 57 . ( 62 - 43 ) - 62 . ( 57 - 43 )

= 57 . 62 - 57 . 43 - 62 . 57 - 62 . 43

= [ 57 . 62 - 62 . 57 ] . [ 62 . 43 - 62 . 43 ]

= 0 . 0 

= 0

a)=(13+47+150)-(13+47)

=(60+150)-60

=210-60

=150

b)=(-237)-(237-155)+55

=(-237)-237+155+55

=(-237)+237-155-55

=0-100

=-100

Ta có: \(A=\frac{4}{7.31}+\frac{6}{7.41}+\frac{9}{10.41}+\frac{7}{10.57}\)

\(=\frac{20}{35.31}+\frac{30}{35.41}+\frac{45}{50.41}+\frac{35}{50.57}\)

\(=5\left(\frac{4}{31.35}+\frac{6}{35.41}+\frac{9}{41.50}+\frac{7}{50.57}\right)\)

\(=5\left(\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}\right)\)

\(=5\left(\frac{1}{31}-\frac{1}{57}\right)\)

\(B=\frac{7}{19.31}+\frac{5}{19.43}+\frac{3}{23.43}+\frac{11}{23.57}\)

\(=\frac{14}{38.31}+\frac{10}{38.43}+\frac{6}{46.43}+\frac{22}{46.57}\)

\(=2\left(\frac{7}{31.38}+\frac{5}{38.43}+\frac{3}{43.46}+\frac{11}{46.57}\right)\)

\(=2\left(\frac{1}{31}-\frac{1}{38}+\frac{1}{38}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}+\frac{1}{46}-\frac{1}{57}\right)\)

\(=2\left(\frac{1}{31}-\frac{1}{57}\right)\)

\(\Rightarrow\frac{A}{B}=\frac{5\left(\frac{1}{31}-\frac{1}{57}\right)}{2\left(\frac{1}{31}-\frac{1}{57}\right)}=\frac{5}{2}\)

Tại sao lại nhân với 2 và 5

vì để tỉ số ấy bằng nhau

D

I DON'T NO

KO TRẢ LỜI THÌ BẠN CÓ K CHO MK KO