Complex sentence: In the ten years of its existence, the school has collected at least 25 state trophies: many of which were won by the cross country team and track and field teams (a combined 8 state championships).
Split into simpler sentences: In the ten years of its existence, the school has collected at least 25 state trophies. Many of these were won by the cross country team and track and field teams (8 state championships).