can Elizabeth exclude the gain from the sale of her house?

1:12-58 On March 10, 2017, Elizabeth, a college professor, purchased a house for $300,000. She did not move into the house until August 8, 2017. On August 1, 2018, she accepted a po- sition as a visiting professor at Hogwatts University for one year and moved to Liverpool where she rented an apartment. While away at Hogwatts, two of her former students lived in the house but did not pay rent. She returned to the house on August 1, 2019, and lived in the house until July 15, 2020, when she sold the house for $500,000. The realtor's commission was $35,000. Determine her recognized gain. A partial list of research sources is: Reg. Sec. 1.121-1(c)