Managerial accounting questions - cost behavious and CVP question

please explain as this is for midterm practice

Mary Ellis owns a small manufacturing company and would like to develop more accurate estimates for overhead expenses when making planning decisions. She is pretty sure that overhead is a mixed cost that varies with direct labour-hours but she would like to do a proper analysis to determine the variable and fixed components. She collected the following information for the past 12 months on direct labour-hours incurred and total overhead expenses. Required: 1. Using the least-squares regression method, estimate the variable overhead cost per direct labour-hour and the total fixed overhead cost per month. (Round Fixed cost to the nearest whole dollar amount and the Variable cost per direct labour-hour to 2 decimal places.) 2. Express the cost data derived in part 1 above in the form Y=a+bX. (Round Fixed cost to the nearest whole dollar amount and the Variable cost to 2 decimal places.) 3. Using the cost formula stated in part 2, estimate total overhead costs for a month where direct labour-hours are expected to be 3,900. (Round your Variable cost per direct labor hour to 2 decimal places and round your final answer to the nearest whole dollar amount.)