Harpes-à-Gonds Fourbe-Riz Total Contribution margin per machine-hour Machine-hours to be worked Contribution margin Fixed costs Operating income €52 1,000 €52,000 €64 1,000 €64,000 €116,000 100,000 Alternatively, we could present Jours-Daim’s operating income by taking two- thirds (1,000 ÷ 1,500 machine-hours) of Harpes-à-Gonds’s January revenues and variable costs and doubling (1,000 ÷ 500 machine-hours) Fourbe-Riz’s January revenues and variable costs.