The Republic Day of India, January 26, 1980, falls on a Saturday.
- X was born on March 3, 1980.
- Y is four days older than X, meaning Y was born on February 28, 1980.
Now, we determine which day of the week February 28, 1980, falls on.
- January 26, 1980 = Saturday.
- Moving forward, February 26 = Tuesday.
- February 27 = Wednesday.
- February 28 = Thursday.
Thus, Y's birthday fell on Thursday.