#3 - Congress may submit a proposed constitutional amendment to the states, if the proposed amendment language is approved by a two-thirds vote of both houses. Congress must call a convention for proposing amendments upon application of the legislatures of two-thirds of the states (i.e., 34 of 50 states).
#5 - Slavery was implicitly recognized in the original Constitution in provisions such as Article I, Section 2, Clause 3, commonly known as the Three-Fifths Compromise, which provided that three-fifths of each state's enslaved population (“other persons”) was to be added to its free population
