Complex sentence: Basu's schooling started at Loreto School at Dharmatala in Kolkata in 1920, and he was moved in 1925 to St. Xavier's School.
Split into simpler sentences: Basu's schooling started at Loreto School at Dharmatala, Calcutta (now Kolkata), in 1920. In 1925, he was moved to St. Xavier's School.