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Đáp án `+` Giải thích các bước giải:

`\bb a)`

`(x+7)-25=13`

`=> x+7= 13+25`

`=> x+7 = 38`

`=> x = 38-7`

`=> x = 31`

`\bb b)`

`87-(73-x)=20`

`=> 73-x = 87-20`

`=> 73-x = 67`

`=> x = 73-67`

`=> x = 6`

`\bb c)` 

`x-105:21=15`

`=> x-5=15`

`=> x = 15+5`

`=> x = 20`

 `\bb d)`

`30+(x+2).2=48`

`=>(x+2).2 = 48-30`

`=> (x+2).2 = 18`

`=> x+2 = 18:2`

`=> x+2 = 9`

`=> x = 9-2`

`=> x = 7`

`\bb e)`

`48-2x=14`

`=> 2x = 48-14`

`=> 2x = 34`

`=> x = 34:2`

`=> x = 17`

`\bb g)`

`18+3.(x-3)=63`

`=> 3.(x-3) = 63 -18`

`=> 3.(x-3) =45`

`=> x-3 = 45:3`

`=> x-3 = 15`

`=> x = 15+3`

`=> x = 18`

`\bb h)`

`[(2x-11):3+1] = 20`

`=> (2x-11):3 = 20-1`

`=> (2x-11):3 = 19`

`=> 2x-11 = 19 xx 3`

`=> 2x-11 = 57`

`=> 2x = 57+11`

`=> 2x = 68`

`=> x = 68:2`

`=> x = 34`

`\bb h)`

`25-3.(6-x)=22`

`=> 3.(6-x) = 25-22`

`=> 3.(6-x) = 3`

`=> 6-x = 3:3`

`=> 6-x = 1`

`=> x = 6-1`

`=> x = 5`