$a) |x| - 7 = 8$
$⇒ |x| = 8 +7$
$⇒ |x| = 15$
$⇒ x = ±15$
$Vậy$ $x ∈$ {$±15$}
$b) 15 - (4-x) =6$
$⇒ 15 -4 +x = 6$
$⇒ 11 +x = 6$
$⇒ x = 6 -11$
$⇒ x = -5$
$Vậy$ $x = -5$
$c) -30 + ( 25 - x) = -9$
$⇒ -30 +25 -x = -9$
$⇒ -5 -x = -9$
$⇒ x = -5 +9$
$⇒ x = 4$
$Vậy$ $x = 4$
$d) x - (12 - 25) = -8$
$⇒ x +13 = -8$
$⇒ x = -8 -13$
$⇒ x = = -21$
$Vậy$ $x = -21$
$e)(x - 29) - (17 - 38) = -9$
$⇒ x -29 +21 = -9$
$⇒ x -8 = -9$
$⇒ x = -9 +8$
$⇒ x = -1$
$Vậy$ $x = -1$