First, let's define expressions for the different rental plans. Let x be the miles driven for both of the plans.
We would have the following:
Plan A: $59.96 initial fee, $0.15 per mile driven

Plan B: $53.96 initial fee, $0.20 per mile driven

Now, since we want to know the required miles driven for the plans to cost the same, we'll have the relation

This way, we would have the equation

Solving for x,

Therefore, Tom would have to drive 120 miles for the two plans to cost the same.
ANSWER: 120