725 x 28 - 14 x 25 x 2 + 300 x 28 

= 725 x 28 - (14 x 2) x 25 + 300 x 28 

= 725 x 28 - 28 x 25 + 300 x 28 

= 28 x ( 725 - 25 + 300 )

= 28 x 1000

 =28000

\(\dfrac{3}{28}+\dfrac{3}{28}+\dfrac{3}{28}+\dfrac{3}{28}=\dfrac{3\times4}{28}=\dfrac{12}{28}=\dfrac{3}{7}\)

3/28+3/28+3/28+3/28=4x3/28=3/7.

a: =13:25=0,25

b: =28+28x8+28=280

\(1357\times28+73\times1357-1357=1357\times\left(28+73-1\right)=1357\times100=135700\)

= 1357(28+73-1)
= 1357x100
= 135700

= 1357 x (28 + 73) - 1357

= 135700

` 10000 – 47 xx 72 – 47 xx 28 `
`=10000-47xx(72+28)`
`=10000-47xx100`
`=100xx100-47xx100`
`=100xx(100-47)`
`=100xx53`
`=5300`

`10 000 - 47 xx 72 - 47xx28`

`=10 000 - 47 xx(72+28)`

`=10 000 - 47xx100`

`=10 000 - 4700`

`=5300`

 10000 – 47 x 72 + 47 x 28 

=10000-(47x(72+28)

=10000-4700

=5300

a) 2070 + 414 x 4 x 28 - 138 x 3 x 17 = 41400

b) 2020 x 14 + 4040 x 16 + 6060 x 18 = 72720

c) 42 x 477 + 14 x 336 x 3 + 84 x 92 - 42 = 41832

a) 2070 + 414 x 4 x 28 - 138 x 3 x 17 = 41400

b) 2020 x 14 + 4040 x 16 + 6060 x 18 = 72720

c) 42 x 477 + 14 x 336 x 3 + 84 x 92 - 42 = 41832

32 + 28 =60

32+28n=60

56 - 5- 9 =42

= 60 +60 -42

=120 -42

=98

đúng ko

16x48+8x48+16x28= 16x48+16x24+16x28

                                =16x(48+24+28)

                                =16x100

                                 =1600

48 x (16+8+16)

=48 x40

=1920