Answer:
Car A: Initial Charge = 20
Car B: Initial Charge = 30
Car A: Rate = 5
Car B: Rate = 0
At 2 miles, their charges will be the same
Explanation:
Given
Car A

per mile
Car B

Solving (a): The initial charge
First, we get the linear equation that represents both car's charges.
Represent number of miles with m.
So, the charges is:
Car A



Set m to 0 to get the initial charge:


and

Car B:
i.e. Rate is 0


So:
and

Solving (b): When their charge wil be equal.
To do this, we set:





At 2 miles, their charges will be equal