If 1st July, 1977 was a Friday then 1st July 1970 was a

There are 7 years between the two except two of them are leap years.

In a normal year, there are 365 days. 365 when divided by 7 leaves a reminder of 1. So, 1 July of a year and 1 July of the previous year are one weekday apart. If it is a leap year, 1 July of a year and 1 July of a previous year are separated by 2 weekdays. So, If July 1, 1977 was a Friday, 1st july 1976 is a Thursday and 1st july 1975-tuesday 1st july 1974-monday 1st july 1973-sunday 1st july 1972-saturday 1st july 1971-thrusday 1st july 1970- wednesday