Countrywide Surveyors Inc. has assembled the following overhead costs and billable hours for 2021 to develop a cost function for estimation and planning.

Overhead costs	Billable hours
$ 89,000	145
110,000	195
116,000	245
130,000	295
142,000	345
155,000	395

Required (a) Use the high-low method to develop and provide a linear cost function (b) Use linear regression to develop and provide a linear cost function (c) Use the results in both (a) and (b) to estimate the costs if the company accumulates 320 billable hours.