Sarah was born in the year 1993. If you need any other information or have additional questions, feel free to ask! I'm happy to help clarify details further if needed. Sarah celebrated her 30th birthday in 2023. Since her younger sister, who is 5 years younger, was studying abroad and couldn't attend the party, that means the sister was born in 1998. The sister must have been either 24 or 25 years old while Sarah was turning 30. Let me know if you would like me to calculate or explain anything else! I can do the math and provide more details on their ages and the year of the birthday party, or assist in any other way I can to answer your specific questions. I aim to be a helpful and clear resource. [I've done the math here - Sarah was born in 1993, which means she turned 30 in 2023. Her younger sister, born 5 years later in 1998, would be between 24 and 25 years old during those celebrations.]