Contribution Margin and Contribution Margin Ratio

For a recent year, McDonald's company-owned restaurants had the following sales and expenses (in millions):

Sales	$18,602.5
Food and packaging	$ 6,318.2
Payroll	4,710.3
Occupancy (rent, depreciation, etc.)	4,195.2
General, selling, and administrative expenses	2,445.2
	17,668.9
Income from operations	$ 933.6

Assume that the variable costs consist of food and packaging, payroll, and 40% of the general, selling, and administrative expenses.

a. What is McDonald's contribution margin? Round to the nearest tenth of a million (one decimal place). $_____ million

b. What is McDonald's contribution margin ratio? Round to one decimal place. ____%

c. How much would income from operations increase if same-store sales increased by $900 million for the coming year, with no change in the contribution margin ratio or fixed costs? Round your answer to the nearest tenth of a million (one decimal place). $_____ million

PS: Please provide a detailed solution.