! Required information [The following information applies to the questions displayed below.] Phillips Company manufactures air-conditioning units for commercial buildings and has noticed considerable variation in shipping expenses from month to month as per the data below: Units Total Shipping Month Shipped Expense January 4 $ 2,360 February 4 $ 3,260 March 5 $ 2,800 April 2 $ 1.314 May 3 $ 2,310 June 6 $ 3,240 July 8 $ 4,704 4. What is the cost formula for shipping expenses?