A major river's drainage basin includes its tributary rivers.
A tributary is a part of a river system that can create a drainage basin.
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A tributary is a smaller river or stream that flows into a larger river, and together with other tributaries, contributes to the formation of a drainage basin, which is the entire area that is drained by a particular river and its tributaries.
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Its awnserd by doing math you idiots stop looking for the awnser and do your own work