The property of inequality that justifies the math in Step 2 is the Addition Property of Inequality.
In Step 2, you are adding (-42) to both sides of the inequality:
\[ -18w + 42 - 42 > -66 - 42. \]
This is an application of the Addition Property of Inequality, which states that if you add (or subtract) the same number from both sides of an inequality, the inequality remains true.