Contribution margin and contribution margin ratio

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

Line Item Description Amount

Sales $$21,000$

Food and paper $$(2,900)$

Payroll and employee benefits $(2,000)$

Occupancy and other expenses $(4,100)$

General, selling, and administrative expenses $(4,000)$

Total $$(13,000)$

Operating income $$8,000$

Assume that the variable costs consist of food and paper, payroll, $25\%$ of occupancy and other expenses, and $40\%$ of the general, selling, and administrative expenses.

a$.$ What is McDonald's contribution margin?

fill in the blank $1$ of $1$$ million

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

fill in the blank $1$ of $1\%$

c$.$ How much would operating income 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$).$

fill in the blank $1$ of $1$$ million