Masters, a Country Y citizen, is an employee of ForeignCorp, a Country Y corporation. On January $1,2023$ she traveled to the U$.$S$.$ on a $1-$year U$.$S$.$ construction project for ForeignCorp. During $2023$ she returned to Country Y to work for two weeks after every two months working in the United States. Masters received two weeks of paid vacation time, which she took while in Country Y$.$ Therefore, she worked $40$ weeks in the United States and $10$ weeks in Country Y$,$ with $2$ weeks vacation in Country Y$.$ During the year her home, family, and closest social, economic, and cultural ties remained in Country Y$.$ Masters worked $5$ days a week while in the U$.$S$.,$ and $5$ days a week when back in Country Y$.$ Masters was not available to work $7$ days a week. Masters was paid a fixed salary of $$144,000$ for the year $($$$12,000$ per month$).$

Issue: During the year $2023,$ how much of the salary is considered U$.$S$.-$source income? Is Masters a nonresident alien?