Complex sentence: Mrs. Carlson has worked as a volunteer in a number of national political campaigns and as a volunteer at the White House in the office of the President for 21 years, and at the residence of the Vice President, two days a week for two years.
Split into simpler sentences: Mrs. Carlson has worked as a volunteer in a number of national political campaigns and as a volunteer at the White House in the office of the President for 21 years. And at the residence of the Vice President, two days a week for two years.