2 câu trả lời
`( -357 + 293 ) - ( 21 - 257 + 193 )`
`= -357 + 293 - 21 + 257 - 193`
`= ( -357 + 257 ) + ( 293 - 193 ) - 21`
`= -100 + 100 - 21`
`= 0 - 21`
`= -21`
( -357 + 293 ) - ( 21 - 257 + 193 )
= -357 + 293 - 21 + 257 - 193
= ( -357 + 257 ) + ( 293 - 193 ) - 21
= -100 + 100 - 21
= 100 -100 -21
= 0 -21
= -21