Answer: Step 1
In Multiplication Property of Equality, you multiply both sides of an equation by the same quantity, to make both sides still equal.
In Trent's case, when he did the Step 1, instead of multiplying both sides by 3, he multiplied 4/3 by 1/3.
Trent should have multiplied both sides by 3, and the solution would look like this
Hence, Trent made a mistake on Step 1.