Which ancient river valley civilization was located along the tigris and euphrates rivers in the land of mesopotamia?
a. sumer
b. memphis
c. mohenjo-daro
d. harappa

- three-quarters or two-thirds..

- "the constitution provides that an amendment may be proposed either by the congress with a two-thirds majority vote in both the house of representatives and the senate or by a constitutional convention called for by two-thirds of the state legislatures."

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