Friday
March 21, 1978 was a Tuesday.
July 21th 1971 was a Wednesday.
monday
It was a Sunday.
That was a Friday. See link to day-of-week calculator.
31 December 1980 was a Wednesday.
1 January 1980 was a Tuesday.
24 February 1980 was a Sunday.
26 January 1980 was a Saturday.
8 August 1980 was a Friday.
13 March 1980 was a Thursday.
6 November 1980 was a Thursday.