Bikes Manufacturing produces and sells children's bikes at an average price of $120. Its costs are as follows: direct materials, $12; direct labour, $6; variable overhead, $4; sales commission, 5% of price. Its xed monthly costs are $54,000. Required: 1. Using the above cost data, set up a monthly cost equation. -:-:- 2. What is the company's contribution margin percentage? (Round your answer to 2 decimal places.)