Gabriel's first step in the equation \(-4(x + -2) = 2\) transforming it to \(-4x + 8 = 2\) is justified by the Distributive Property.
The Distributive Property states that for any three numbers \(a\), \(b\), and \(c\):
\[ a(b + c) = ab + ac \]
In Gabriel’s case, he applied the Distributive Property by distributing \(-4\) to both \(x\) and \(-2\):
\[ -4(x + -2) = -4x + (-4)(-2) = -4x + 8 \]
Thus, the justification for Gabriel's first step is indeed the Distributive Property.