Complex sentence: His parents worked on a collective farm: Alexey Ivanovich Gagarin as a carpenter and bricklayer, and Anna Timofeyevna Gagarina as a milkmaid.
Split into simpler sentences: His parents worked on a collective farm. His father, Alexei Ivanovich Gagarin was a carpenter and bricklayer, and his mother, Anna Timofeyevna Gagarina, was a milkmaid.