To calculate the year someone should finish high school if they were born in 1973, we need to know the typical duration of high school education. In most countries, high school lasts for four years. Assuming the person started high school at the typical age of 14, we can add four years to 1973 to get the expected year of high school completion.
1973 + 4 = 1977
So, someone born in 1973 would typically finish high school in 1977. However, it's possible that the person started high school earlier or later than the typical age or may have taken longer to complete their studies.