You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
In this task, you are given a question. You have to answer the question based on your information.

Roman Yakub won first price in a Choral Composition Competition at a liberal arts college founded by who?
Solution: William Egbert
Why? This is a good example, and output correctly answers the question.

New input: Trade beads (sometimes called aggry and slave beads) were otherwise decorative glass beads used between the 16th and 20th century as a token money to exchange for goods, services and slaves (hence the name), this included the African slave trade, slavery has existed in Africa for how long?
Solution:
many centuries