Assume that a company has two cost driversnumber of graphing calculators and number of customers. The planned number of graphing calculators and customers were 5 and 100, respectively. The actual number of graphing calculators and customers were 6 and 110, respectively. One of the companys expenses is influenced by both cost drivers. Its cost formulas are $50 per graphing calculator and $5 per customer. The total actual amount of this expense is $880. The spending variance for this expense would