Bài 15:

i)28 . (231+69)+72 . (231+69)         m)53 . 11+79 . 101          n)17 . 85+15 . 17

=28 . 300+72 . 300                          =583+7979                     =17 . (85+15)

=300 . (28+72)                                 =6562                             =17 . 100

=300 . 100                                                                               =1 700

=30 000

Bài 16:

c)13 . 17 - 256 : 16+14 :7 - 1        b)12 : {400 : [500- (125+25 . 7)]}      d)18 : 3 + 182 + 3 . (51 : 17)

=221 - 16 + 2 - 1                         =12 : {400 : [500- (125+175)]}          =6 +182 + 3 . 3

=205 +2 - 1                                 =12 : {400 : [500 - 300]}                    =6 +182 + 9  

=207 - 1                                      =12 : {400 : 200}                                =188 +9

=206                                            =12 : 2                                              =197

                                                    =6

i) ???????                                      *){46 - [(16 + 71 . 4) : 15]} -2

                                                    ={46 - [(16+284) : 15]} - 2

                                                    ={46 - [300 : 15]} - 2

                                                    ={46 - 20} - 2

                                                    =26 - 2

                                                    =24

Viết lại câu i bạn nhé! Chúc hoc tốt và cho mik ctlhn. Khi nào bạn sửa lại câu i bài 16 mik sẽ làm típ

`15)`

`1)28. ( 231+ 69 ) + 72. ( 231 + 69 )`

`=28.300+72.300`

`=(28+72).300`

`=100.300`

`=30 000`

`m)53.11 + 79. 101`

`=583+7979`

`=8562`

`n) 17 . 85 +15 . 17 - 120`

`=17.(85+15)-120`

`=17.100-120`

`=1700-120`

`=1580`

`16)`

`c) 13. 17 - 256 : 16 + 14 : 7 - 1`

`=91-16+2-1`

`=75+1`

`=76`

`b) 12: {400:[500- ( 125+ 25.7 )]}`

`=12:{400:[500-(125+175)]}`

`=12:{400:[500-300]`

`=12:{400:200}`

`=12:2`

`=6`

`d) 18: 3 + 182 + 3. ( 51: 17)`

`=6+185.3`

`=6+555`

`=561`

`i) 5[ ( 85 - 35 : 7 ) : 8 + 90 ] - 50 . { 46 - [( 16 + 71.4 ) : 15 ]} - 2.`

`=5.[(85-5):8+90]- 50 . { 46 - [( 16 + 284 ) : 15 ]} - 2.`

`=5.[80:8+90]-50.{46-[300:15]}-2`

`=5.[10+90]-50.{46-20}-2`

`=5.100-50.26-2`

`=500-1300-2`