Monday
In order to know what day of the week a day in February 1985 was one needs to know the date in February.
February 29th, 1985 was actually a leap year. So, this day of the week did not occur.
January 9 1979 was a Tuesday.
November 4th, 1979 was on a Sunday.
March 18 1979 was a Sunday.
2 February 1979 was a Friday.
4 February 1979 was a Sunday.
19 February 1979 was on a Monday.
18 February 1979 was a Sunday.
February 12, 1979 was a Monday.
February 7, 1979 was a Wednesday.
February 20, 1979 was a Tuesday.
24 February 1979 was a Saturday.
February 6 1979 was a Tuesday.
February 10 1979 was a Saturday.
February 17, 1979, was a Saturday.
February 13, 1979 fell on a Tuesday.