The Life of Sarah

• Sarai

• Start — Genesis 17:17. The year of Sarai's birth is the the year her husband,Abram, was born (2010) + their difference in age (10 years) = 2020
• End — Genesis 23:1. The year of Sarai's death is the year she was born (2020) + her age at death (127) = 2147

Sarah was 90 when Abraham was 100 so she was 10 years younger than Abraham. (GEN 17:17)

Years are anno hominis — counted from Creation as year 1 — which is the frame the source computes in. The arithmetic behind each boundary is given above rather than assumed.