Complex sentence: Wickremanayake first served as Prime Minister from August 2000 to December 2001, succeeding his mother Sirimavo Bandaranaike, who resigned from the position at the age of 84.
Split into simpler sentences: Wickremanayake first served as Prime Minister from August 2000 to December 2001. He succeeded Sirimavo Bandaranaike after she resigned from the position at the age of 84.