Tom initially argues that executives earning 85 times more than the average worker is an "extraordinarily large disparity," and so concludes that public resentment over executives' salaries is justified.

Martha rejects Tom's argument, arguing that because most people aren't willing to take the risks and make the decisions that create wealth, "generous rewards" for people who do are "both fair and necessary," and resentment of executives' salaries is not justified.

Tom responds by claiming that Martha misunderstood his argument. He clarifies that he was not talking about people resenting the fact that there is simply a large disparity between executives' and workers' salaries, but about people resenting the unusually large disparity that exists in this country. He notes that in other countries, executives only earn 20-30 times the average worker's salary.

What Martha and Tom are disagreeing on is whether the scale of the disparity between executives' and workers' salaries in Tom and Martha's country — executives earning 85 times as much as workers — is large enough to justify people resenting executives' salaries. Martha's argument makes it clear that she doesn't think so — she thinks the executives' salaries are "both fair and necessary" — while Tom's response to Martha emphasizes that, while Tom might agree that executives deserve more compensation than workers, the scale of the disparity in their country is "extraordinary" or "atypical" (i.e., beyond what is "fair and necessary"), and that people's resentment over the disparity is therefore justified. Notice the way Tom supports this claim that the disparity is "atypically large," and therefore the claim that public resentment is legitimate: by pointing out that other countries have much smaller disparities.