Answer:
2. The professor’s warm, gentle voice soothed the weary, frustrated students.
Rule: The comma may be used between the adjectives "warm and kind" and "tired and frustrated" according to the rule.
3. The Maya are famous for their calendar, and the Aztecs are notorious for their human sacrifices.
Rule: Since "and the Aztecs" is a coordinating conjunction, it should be followed by a comma to indicate its position before the first independent sentence it introduces.
Step-by-step explanation:
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