Comparing Contribution Margin Percentages Following are actualstatements of operating income for Microsoft and Procter \& Gamble (in millions): Assume that the only variable cost for Microsoft is "cost of revenue" and for Procter \& Gamble the only variable cost is "cost of products sold." 1. Compute the contribution-margin percentage of Microsoft and that of Procter \& Gamble. 2. Suppose each company increases its revenue by $10 million. Compute the increase in operating income for each company