Why is the Missouri Compromise of 1820 considered a temporary solution to the slave issue? (3+ sentences)

The missouri compromise of 1820 was considered a temporary solution as it decided that states above the 35’30 line would be free states and the states below would be slave states. The addition of more states to the union would cause an inequality in the amount of slave and free states. Therefore, more disagreements about the addition of new slave and free states would bring more problems.

Andrei karlov was the russian ambassador