Complex sentence: He served as Deputy Finance Minister in Mexico from 2000 to 2003, when he was appointed Deputy Managing Director at the International Monetary Fund, and was responsible for handling the IMF's relationship with more than 70 member countries.
Split into simpler sentences: He served as Deputy Finance Minister in Mexico from 2000 to 2003. Then he was appointed Deputy Managing Director at the International Monetary Fund and was responsible for handling the IMF's relationship with more than 70 member countries.