Complex sentence: He appears at Farkle's career day at school, whereupon he instantly renews his rivalry with both Cory and Topanga, and is proud to mention his position as the CEO of Minkus International.
Split into simpler sentences: He appears at Farkle's career day at school whereupon he instantly renews his rivalry with both Cory and Topanga. He is proud to mention his position as the CEO of Minkus International.