Ch. 9 - Jason's Deli Catering uses a standard cost function, Y = a + bx, to estimate costs for the budgets it prepares. The costs Jason's Deli has estimated for catering services for each event is $1,000 plus $7.50 per guest. During December, Jason's Deli planned an event for an expected guest count of 100 guests, however the actual number of guests was 90. The costs incurred in December for catering was $1,900. The spending variance for the catering event operating cost for the month of Dcember would be closest to