Luke's Diner sells three different kinds of coffee in 5 lb bags.

• The light roast sells for $30 and has variable costs of $18
• The medium roast sells for $50 and has variable costs of $30
• The dark roast sells for $70 and has variable costs of $45

The sales mix of the three sets is: Light, 50%; Medium, 30%; and Dark, 20%.

What is the weighted-average unit contribution margin?

Provide numerical response only, no comma or dollar sign needed.