A department of Alpha Co. incurred the following costs for the month of September. Variable costs, and the variable portion of mixed costs, are a function of the number of units of activity:

Activity level in units		3,500
Variable costs	$	7,000
Fixed costs		30,000
Mixed costs		21,100
Total costs	$	58,100

During October the activity level was 7,800 units, and the total costs incurred were $68,500.

Required:

a. Calculate the variable costs, fixed costs, and mixed costs incurred during October.

b. Use the highlow method to calculate the cost formula for mixed cost. (Do not round intermediate calculations and round your answers to 2 decimal places.)