Adam uses the high-low method to estimate total monthly maintenance costs for his Rock & Soil company. He uses maintenance hours as the cost driver. Data for several months are shown: Maintenance hours Total_maintenance costs Jan. 100 $500 Feb. 80 5480 Mar. 120 5640 Apr. 160 5600 Based on the high-low method, the total foxed costs are O 5500 O $150 5360 $180