Complex sentence: He had a strong affection for mathematics, and would have liked to study in this or a related area, but as the financial situation of the family opposed further education, he decided to become a merchant and began an apprenticeship in Stuttgart.
Split into simpler sentences: He had a strong affection for mathematics and would have liked to study in this or a related area. But as the financial situation of the family opposed further education, he decided to become a merchant and began an apprenticeship in Stuttgart.