`#3107.101107`
A.
`-7 + x = -3`
`=> x = -3 - (-7)`
`=> x = -3 + 7`
`=> x = 4`
Vậy, `x = 4`
B.
`-456 - x = 723`
`=> x = -456 - 723`
`=> x = -1179`
Vậy, `x = -1179`
C.
`-124-312 + x = -415`
`=> -436 + x = -415`
`=> x = -415 - (-436)`
`=> x = -415 + 436`
`=> x = 21`
Vậy, `x = 21`
D.
`-214+512-(-163)-x=-768- (-423)`
`=> 298 - (-163) - x = -345`
`=> 298 + 163 - x = -345`
`=> 461 - x = -345`
`=> x = 461 - (-345)`
`=> x = 461 + 345`
`=> x = 806`
Vậy, `x= 806.`
a: x-7=-3
=>x=-3+7=4
b: -456-x=723
=>x=-456-723=-1179
c: -124-312+x=-415
=>x-436=-415
=>x=21
d: -214+512-(-163)-x=-768-(-423)
=>461-x=-345
=>x=461+345=806
\(A)-7+x=-3\\\Rightarrow x=-3-(-7)\\\Rightarrow x=-3+7\\\Rightarrow x=4\\Vậy:x=4.\\---\\B)-456-x=723\\\Rightarrow x=-456-723\\\Rightarrow x=-1179\\Vậy:x=-1179.\\---\)
\(C)-124-312+x=-415\\\Rightarrow (-124-312)+x=-415\\\Rightarrow -436+x=-415\\\Rightarrow x=-415-(-436)\\\Rightarrow x=-415+436\\\Rightarrow x=21\\Vậy:x=21.\\---\\D)-214+512-(-163)-x=-768-(-423)\\\Rightarrow [-214+512-(-163)]-x=-768+423\\\Rightarrow [298-(-163)]-x=-345\\\Rightarrow (298+163)-x=-345\\\Rightarrow 461-x=-345\\\Rightarrow x=461-(-345)\\\Rightarrow x=461+345\\\Rightarrow x=806\\Vậy:x=806.\)
\(Toru\)
\(-7+x=-3\\ \Rightarrow x--3-\left(-7\right)\\ \Rightarrow x=-3+7\\ \Rightarrow x=4\\ -456-x=723\\ \Rightarrow x=-456-723\\ \Rightarrow x=-1179\\ -124-312+x=-415\\ \Rightarrow312+x=-124+415\\ \Rightarrow312+x=291\\ \Rightarrow x=291-312\\ \Rightarrow x=-21\\ -214+512-\left(-163\right)-x=-768-\left(-423\right)\\ \Rightarrow-214+512+163-x=-345\\ \Rightarrow512+163-x=-345+214\\ \Rightarrow512+163-x=-131\\ \Rightarrow163-x=-131-512\\ \Rightarrow163-x=-643\\ \Rightarrow x=163+643\\ \Rightarrow x=806\)