How can a large group of people with widely different backgrounds, beliefs and interest work together to form one political union

Prior to the presence of europeans on the continent, the slave trade in africa a) did not exist in any form. b) was limited to internal trade only. c) included the trans-saharan and indian ocean slave trade. d) was rarely needed due to the lack of an agricultural economy.

Why must governments be able to compromise?

Which statement is true of both presidential and parliamentary systems of government?