Wilmington Corporation has a total expense per unit of $1.50 at the 15,000 unit level of activity and total expense per unit of $1.45 at the 20,000 unit level of activity. Assume that the relevant range includes all of the activity levels mentioned in this problem. What would be the variable cost per unit for Wilmington Corporation? $0.77 O $1.50 O $1.30 O $1.45