Below are the processing costs of Hartley Products observed over the last ten months: Month Processing Cost 1 2 3 4 Units Produce d 9,600 14,000 15,000 5,500 9,000 8,500 3,500 7,000 12,500 6,000 5 $52,000 57,000 59,000 38,000 47,000 52,000 32,000 41,000 53,000 41,000 6 7 8 9 10 *** Use the high low method to determine the variable cost per unit and fixed cost per month. Express your results in the form of a linear equation y = a + bx. Predict the total processing cost if 12,000 units are produced. Why do we use high low method