To calculate the contestant's balance of prize money, we need to determine the total amount lost for the 6 wrong answers.
The contestant loses $12.50 for each wrong answer. Therefore, for 6 wrong answers:
\[ 6 \text{ wrong answers} \times -12.50 \text{ dollars/wrong answer} = -75.00 \text{ dollars} \]
This means the contestant's balance of prize money is \(-75.00\).
So the correct answer is:
−$75.00 (or "negative $75.00").