Academy Products manufactures a variety of custom components for use in aircraft navigation and communication systems. The management accountant has asked for your help in estimating fixed and variable overhead costs for the Academys Canterbury factory. The accountant believes that the best cost driver for estimating the overhead costs is the number of machine hours. Monthly data on machine hours and overhead costs for the last year are as follows:

Month	Machine Hours	Overhead costs
Sep	900,000	$1,070,000
Oct	765,000	$1,220,000
Nov	665,000	$795,000
Dec	990,000	$1,261,000
Jan	800,000	$920,000
Feb	750,000	$1,100,000
Mar	815,000	$1,230,000
Apr	935,000	$1,450,000
May	833,000	$1,645,000
Jun	590,000	$800,000
Jul	750,000	$1,110,000
Aug	580,000	$810,000

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(a) Estimate the unit variable cost per machine hour and the monthly fixed cost using the high-low method and write the total cost formula. (Show your working).

(b) Using the total cost formula derived in (a), estimate the total overhead cost for September if the machines are operating for 850,000 hours. (Show your working).