4. The sales and cost data for two compan ies in the transportation industry are as follows X Company Amount Percen Percent 100 60 Amount $120,000 36,000 84,000 72,000 100 30 Sales Variable costs Contribution margin Fixed costs Operating income $120,000 72,000 48,000 40 36,000 $ 12.000 X Company's degree of operating leverage (DOL) at the current sales volume level is calculated to be