The mayans contributed to astronomy, biology, and the mathematical comcept of
a. zero
b. algebra
c. geometry
d. powers of ten

The correct answer is a. The Mayans had very advanced math, which aided their astronomy and arquitectural pursuits. They used a numerical system based on powers of twenty (the Hindu-Arabic system, used nowadays around the world, uses powers of ten). A shell shape was used to mark the number zero.

-an amendment is proposed.

-two-thirds of congress must approve.

-thee-quarters of states must approve.

-the proposed amendment becomes law.

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