Bikes Manufacturing produces and sells children's bikes at an average price of $140. Its costs are as follows: direct materials, $13; direct labour, $9; variable overhead, $2; sales commission, 5% of price. Its fixed monthly costs are $48,000. Required: 1. Using the above cost data, set up a monthly cost equation. X 2. What is the company's contribution margin percentage? (Round your answer to 2 decimal places.) Contribution margin