Explain the decreasing trend in hiv cases from the late 90's to 2016.

HIV was identified, and studied, showing possible solutions to the disease, and what caused it.  

the main reason that the constitution did not proclaim all men to be free and equal is because of the issue of slavery.

while it was true that the cotton gin reduced the labor of removing seeds, it did not reduce the need for slaves to grow and pick the cotton.

explanation:

before eli whitney's invention of the cotton gin, picking and cleaning cotton was a slow, labor-intensive job. workers, usually slaves, had to pick the seeds from the cotton fibers by hand. this invention made it possible to grow large amounts of cotton on big farms and make money.