Many words can be formed from a single root by adding common prefixes and suffixes.
about one-third of american words come from latin or greek.

Both statements are correct.

Explanation:

The root is an immutable part of the word. It refers to the semantics of the word, its context of creation (formation) and its transformations until its current use. The root reference is the basic identification of a group of words, by their graphic similarities. Thus, we can conclude that many words can be formed from a single root by adding common prefixes and suffixes. Words that have the same root form a lexical family and are called cognates. Greek influenced Latin, especially in vocabulary. Greek was a language with a remarkable literature, and so the Latin writers came to seek him above all many words, especially those of philosophical bias. On the other hand, Latin, besides being the base language of many languages in the American continent, was the language to which, especially in the Renaissance, the humanists sought new terms, most of which still remain; many of the Greek origin had entered Latin, as I said, from the time when this language was alive, that is, when it had not yet been fragmented into the different Romance languages. These two languages had great influence in the whole American territory composing about one-third of the American words.