Complex sentence: Olson attended Buchanan High School in Clovis, California, and Cal Poly for college, where in his last year he was 12-4 with a 2.71 ERA.
Split into simpler sentences: Olson attended Buchanan High School in Clovis, California. He attended California Polytechnic for college, where in his last year he was 12-4 with a 2.71 ERA.