What was the price of a first class stamp in 1980?
It will depend specifically an what you mean by a stamp book. Is it a small collection of stamps issued in 1980? Is it a small collection sold in 1980 with stamps from different years? Is it simply a book about the stamps? The catalog or purchase price of stamps can be found by consulting a catalog, usually available in the reference section of your library. Selling is usually at 25% of that price.
In 1980 it was probably Queen Elizabeth II as she is pictured on all British Stamps. It would be difficult to determine what country issued the first stamp with a woman on it in that year as it is pretty common these days. In the US it would be Frances Perkins (April 10, 1880 - May 14, 1965), who was the U.S. Secretary of Labor from 1933 to 1945.