Question: How many Grand Slam singles championships were won by the winner of the 1974 Virginia Slims of Newport?

Context paragraphs:
Chris Evert: Christine Marie Evert (born December 21, 1954), known as Chris Evert Lloyd from 1979 to 1987, is a former World No. 1 professional tennis player from the United States.  She won 18 Grand Slam singles championships and three doubles titles.  She was the year-ending World No. 1 singles player in 1974, 1975, 1976, 1977, 1978, 1980, and 1981.  Overall Evert won 157 singles championships and 32 doubles titles.

1974 Virginia Slims of Newport: The 1974 Virginia Slims of Newport, was a women's tennis tournament played on outdoor grass courts at the Newport Casino in Newport, Rhode Island in the United States that was part of the 1974 Virginia Slims World Championship Series.  It was the fourth edition of the tournament and was held from August 22 through August 26, 1974.  First-seeded Chris Evert won the singles title and earned $4,500 first-prize money.

1974 Virginia Slims of Akron: The 1974 Virginia Slims of Akron, also known as the Akron Tennis Open, was a women's tennis tournament played on indoor carpet courts at the University of Akron Memorial Hall in Akron, Ohio in the United States and was part of the 1974 Virginia Slims circuit.  It was the second edition of the tournament and was held from March 18 through March 24, 1974.  Billie Jean King won the singles title and the accompanying $10,000 first-prize money.

1974 Virginia Slims Championships: The 1974 Virginia Slims Championships were the third season-ending WTA Tour Championships, the annual tennis tournament for the best female tennis players in singles on the 1974 Virginia Slims circuit.  It was held from October 14–19, in Los Angeles, United States.  The 16 best performers of the circuit qualified for the championship as well as the four best doubles teams.  Third-seeded Evonne Goolagong won the singles title and the accompanying $32,000 first prize.

1974 Virginia Slims of Detroit: The 1974 Virginia Slims of Detroit was a women's tennis tournament played on indoor carpet courts at the Cobo Hall & Arena in Detroit, Michigan in the United States that was part of the 1974 Virginia Slims World Championship Series.  It was the third edition of the tournament and was held from February 20 through February 24, 1974.  First-seeded Billie Jean King won the singles title and earned $10,000 first-prize money.

1974 Virginia Slims of Denver: The 1974 Virginia Slims of Denver was a women's tennis tournament played on indoor carpet courts at the Denver Auditorium Arena in Denver, Colorado in the United States that was part of the 1974 Virginia Slims World Championship Series.  It was the third edition of the tournament and was held from September 23 through September 29, 1974.  Third-seeded Evonne Goolagong won the singles title and earned $10,000 first-prize money.

1974 Virginia Slims of Washington: The 1974 Virginia Slims of Washington was a women's tennis tournament played on indoor carpet courts at the James Robinson School Field House in Fairfax, Virginia in the United States that was part of the 1974 Virginia Slims World Championship Series.  It was the third edition of the tournament and was held from January 28 through February 3, 1974.  First-seeded Billie Jean King won the singles title and earned $10,000 first-prize money.

1974 Virginia Slims of Houston: The 1974 Virginia Slims of Houston was a women's tennis tournament played on indoor carpet courts at the Net-Set (West Side) Racquet Club in Houston, Texas in the United States that was part of the 1974 Virginia Slims World Championship Series.  It was the fourth edition of the tournament and was held from September 30 through October 6, 1974.  First-seeded Chris Evert won the singles title and earned $10,000 first-prize money.

1974 Virginia Slims of Philadelphia: The 1974 Virginia Slims of Philadelphia was a women's tennis tournament played on indoor carpet courts at the Palestra in Philadelphia, Pennsylvania in the United States that was part of the 1974 Virginia Slims World Championship Series.  It was the third edition of the tournament and was held from April 22 through April 28, 1974.  Seventh-seeded Olga Morozova won the singles title and earned $10,000 first-prize money.

1974 Virginia Slims of Chicago: The 1974 Virginia Slims of Chicago was a women's tennis tournament played on indoor carpet courts at the Lake Shore Racquet Club in Chicago, Illinois in the United States that was part of the 1974 Virginia Slims World Championship Series.  It was the third edition of the tournament and was held from February 25 through March 3, 1974.  Fourth-seeded Virginia Wade won the singles title and earned $10,000 first-prize money.

Supporting paragraphs: 1974 Virginia Slims of Newport Chris Evert
Answer: 18