Jake's Roof Repair has provided the following data concerning its costs: Fixed Cost Cost per per Month Repair-Hour Wages and salaries $ 21, 200 $15.00 Parts and supplies $ 7.40 Equipment depreciation $ 2, 700 $ 0. 30 Truck operating expenses $ 5, 750 $ 1. 70 Rent $ 4, 650 Administrative expenses $ 3, 870 $ 0. 60 For example, wages and salaries should be $21,200 plus $15.00 per repair-hour. The company expected to work 2,900 repair-hours in May, but actually worked 2,800 repair-hours. The company expects its sales to be $46.00 per repair-hour. Required: Compute the company's activity variances for May. (Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable, and "None" for no effect (i.e., zero variance). Input all amounts as positive values.)