Relevant Costing: Homer Enterprises, which produces various goods, has limited processing hours at its manufacturing plant. The following data apply to product no. 607:

Sales price per unit: $9.60 Variable cost per unit: $6.20 Process time per unit: 4 hours

Management is now studying whether to devote the firm's limited hours to product no. 607 or to other products. What key dollar amount should management focus on when determining no. 607's "contribution" to the firm and deciding the best course of action to follow?