Row and Column Sums in a Calendar

The following is an example of the days of May 2024 shown on a conventional calendar, with rows showing dates from Sunday to Saturday from left to right in that order. For the date May 18, 2024, the day is Saturday and the day number is 18. In a conventional calendar, for a given date in another month, the sum of the day numbers on the same row as that date is 77, while the same of the day numbers on the same column as that date is 66. What is the day and day number of that date?