Answer:
$116.28
Explanation:
This can be calculated as follows:
Mark up = [1 ÷ (1 - Lerner index)]
Price = Mark-up × Marginal cost
    = [1 ÷ (1 - 0.57)] × $50
Price = [1 ÷ 0.43] × $50 = $116.28 Â
Therefore, the price this firm will charge its customers is $116.28.