The justification for the steps shown in the solution process is the Multiplication Property of Inequality.
This property states that if you multiply both sides of an inequality by a positive number, the direction of the inequality remains the same. In your case, multiplying both sides of the inequality \(43d \geq -20\) by \(34\), a positive number, leads to \(34(43d) \geq 34(-20)\) and simplifies down to \(d \geq -15\).