How did the Maya, Aztec, and Inca build impressive cities? in your own words

The Mayas, for example, made striking advances in writing, astronomy, and architecture. Both the Mayas and the Aztecs created highly accurate calendars. The Aztecs adapted earlier pyramid designs to build massive stone temples. The Incas showed great skill in engineering and in managing their huge empire.

Explanation:

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a system in which products were made rapidly by machines

answer; i believe the two groups were irish immigrants and chinese immigrants;