x-205=487

x=487+205

x=692

x - 205 = 487

x          = 487 + 205

x          = 692

` x:248=1000 -862 `

`=> x:248=138`

`=> x=138 xx 248`

`=>x= 34224`

__

`  x-72980:356=487`

`=> x-72980=487 xx 356`

`=> x-72980=173372`

`=>x=173372+ 72980`

`=>x= 246352`

`@ yngoc`

\(-87+\left(-12\right)-\left(-487\right)-\left(-487\right)+512\)

\(=-87+\left(-12\right)+487+487+512\)

=\(\left(\left(-12\right)+512\right)+\left(\left(-87\right)+487\right)+487\)

=\(500+400+487\)

\(=900+487\\ =1387\)

=-87+(-12)+487+487+512

=((-12)+512)+((-87)+487)+487

=500+400+487

=900+487

1387

356x41+356x35+356x23+356
=356x(41+35+23+1)
=356x100
=35600

356*41+356*35+356*23+356

356*(41+35+23+1)

356*100=35600 :)))

487 x 789 + 487 x 211

= 487 x ( 789 + 211 )

= 487 x 1000

= 487 000

456 + 324 + 456 + 1234

= 780 + 1690

= 2470 

4567 + 1278 + 1224

= 5845 + 1224

= 7069

=479899

=2470

=7069

Chọn B

C

Đáp án:

= 356 . (445 - 245 )

= 356 . 200

= 71200

356(445-245)
= 356. 200
=71200

 

- 87 + ( - 12 ) - ( - 487 ) + 512

= - 87 + ( - 12 ) + 487 + 512

= -87 + 487 + ( - 12 ) + 512

= 400 + 500

= 900

900

(-87) + (-12) + 487 + (-512)

= (-87 + 487) - (12 + 512)

= 400 - 524

= -124

( -87) + (- 12) + 487 + (- 512)

= [ (-87) + 487] +  [(- 12) + (- 512)]

= 400 +  (- 524)

= -124