The managing director of a law firm has the monthly data $($below$)$ on total overhead costs and professional labor hours to bill to clients. Develop a simple linear regression model between billable hours and overhead costs.

$\backslash$table$[[\backslash$table$[[$Overhead$],[$Costs$]],\backslash$table$[[$Billable$],[$Hours$]]],[375000,3000],[425000,4000],[445000,5000],[496000,6000],[580000,7000],[605000,8000]]$

Round the coefficient to two decimal places, do not include the $ symbol. For each increase of $1$ unit in billable hours, the predicted overhead costs are estimated to increase by