Example with a context (Yahoo news story: South Carolina House approves bill removing Confederate flag):
The House easily approved the Senate bill by a two-thirds margin (94-20), and the bill now goes to Republican Gov. Nikki Haley's desk. She supports the measure, which calls for the banner to come down within 24 hours of her signature.
What does that exactly mean? Two-thirds obviously means two out of three. But what is a two-thirds margin?