Xanadu Engine Repairs provides maintenance and repair services for small engines such as those found in lawn mowers, power saws, and snow throwers. The repair shop costs include the salaries for the mechanics, insurance and depreciation on the repair equipment, materials and parts used for the jobs, and utilities. The repair shop manager would like to develop a model for predicting repair costs and over the past 10 months has carefully recorded the total repair costs incurred, along with the number of maintenance and repair jobs completed each month. The data are shown below: a. Using the high-low method, estimate a cost formula for repair costs. Show all your work and express the formula in the form Y=a+bX(5 marks ) b. Explain why it is helpful to have a cost formula and how it can be used ( 2 marks). 0. If the company wanted a better tool, what would you recommend and why? (2 marks)