Complex sentence: Nigeria is a Federal Republic modeled after the United States, with executive power exercised by the president and with influences from the Westminster System model in the composition and management of the upper and lower houses of the bicameral legislature.
Split into simpler sentences: Nigeria is a Federal Republic modelled after the United States, with executive power exercised by the president. The government of Nigeria is also influenced by the Westminster System model in the composition and management of the upper and lower houses of the bicameral legislature.