Complex sentence: This last position she held till 1941, when she retired at the age of 70: since she was unsuccessful to establish a pension system for teachers, she decided to take a leave of absence instead of a retirement without benefits.
Split into simpler sentences: This last position she held till 1941, when she retired at the age of 70. As she was unsuccessful in establishing a pension system for teachers, she decided to take a leave of absence instead of a retirement without benefits.