Jake's Roof Repair has provided the following data concerning its costs:

	Fixed Cost Per Month	Cost per Repair-Hour
Wages and Salaries	$20,700	$15.00
Parts and Supplies		$7.70
Equipment depreciation	$2,730	$0.30
Truck Operating Expenses	$5,750	$1.80
Rent	$4,670
Administrative expenses	$3,890	$0.50

For example wages and salaries should be $20,000 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 $51.00 per repair-hour.

Compute the company's activity variances for May. (Indicate the effect of each variance by choosing "F" for favorable, "U" for unfavorable, and "None" for no effect (i.e., zero variance).

please show explanations! thanks