The establishment of 18 as the age to vote is an information amendment to the constitution

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if you looking for which amemdment, The 26th Amendment: “Old Enough to Fight, Old Enough to Vote”

worldwide, 780 million people do not have access to an improved water source. an estimated 2.5 billion people lack access to improved sanitation (more than 35% of the world's population)

independent innovation during the abbasid caliphate