Complex sentence: He attended Northridge Military Academy, Canoga Park High School in the 10th and 11th grades; nonetheless he graduated co-valedictorian (along with Mare Winningham) of the 1977 of Chatsworth High School in Chatsworth, California.
Split into simpler sentences: He attended Northridge Military Academy, Canoga Park High School in the 10th and 11th grades. He graduated co-valedictorian (along with Mare Winningham) of the class of 1977 of Chatsworth High School in Chatsworth, California.