To find the possible values of x, first we mus simplify the inequality
-18 + 6x ≥ 4x + 12
6x - 4x ≥ 12 + 18
2x ≥ 30
x ≥ 15
From this, it can be seen that as long as x is equal or more than 15, then it will satify the equation. In mathematicl expression, that means [15, ∞).
Thus, the answer is D: [15, ∞).
