How did the Missouri compromise keep the balance of power in the senate

See explanation.

Explanation:

The Missouri Compromise provided for the entrance of Maine as a free state and Missouri as a slave state. Since the North (anti-slavery) and the South (pro-slavery) each contained 11 states consisting of 2 votes in the Senate each, the Senate was entirely balanced on the issue of slavery. Missouri, however, sought to upset this balance by seeking admission as a slave state. In order to remedy this situation and maintain the balance of power, Congress agreed to admit Missouri as a slave state so long as Maine could also be admitted as a free state to counteract it.