a) 15 – ( 4 – x) = 6
4 - x = 15 - 6
4 - x = 9
x = 4 - 9
x = -5
vậy x=-5
b) - 30 + ( 25 – x) = - 1
25 - x = -1 -(-30)
25 - x = -1 +30
25 - x = 29
x = 25 - 29
x = -4
vậy x = - 4
c) x – ( 12 – 25) = -8
x - (-13) = -8
x =-8 + (-13)
x = -21
vậy x=-21
d)( x – 29 ) – ( 17 – 38 ) = - 9
( x - 29 ) - (-21) =-9
x - 29 =-9 + (-21)
x - 29 = -30
x = -30 + 29
x =-1
vậy x=-1