How many countries are there in west africa?
No context provided
How many official countries are there in West Africa?
16
No context provided
How many official countries are there in West Africa, if you include the United Kingdom Overseas Territory of Saint Helena, Ascension and Tristan da Cunha?
17
West Africa
https://en.wikipedia.org/wiki/West%20Africa
West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 17 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, and Togo as well as Saint Helena, Ascension and Tristan da Cunha.[8] 
West Africa
West Africa or Western Africa is the westernmost region of Africa, and officially has 16 countries.  Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, and Togo, and if you include the United Kingdom Territory of Saint Helena, Ascension and Tristan da Cunha, there are 17. 