In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
Q: Passage: Having left Casablanca Records, with whom she had had some of the biggest selling and most popular hits of the disco era in the 1970s, Summer had signed to Geffen Records in 1980 and had continued working with Giorgio Moroder and Pete Bellotte, with whom she had written the vast majority of her hits. However, label owner David Geffen had been disappointed with the chart performance of the 1980 The Wanderer, Summer's debut album for Geffen and rather than release the followup; I'm a Rainbow which Summer had recorded with Moroder/Bellotte in 1981. Geffen had Summer record a new album with Quincy Jones from whom a production credit given Jones' track record particularly his work with Michael Jackson Geffen felt would guarantee a commercial smash. The resultant Donna Summer album was the first time the singer had worked with a producer other than Moroder and Bellotte since 1974 save for the one-off track "Down Deep Inside (Theme from "The Deep")" which was produced by John Barry for the film The Deep, and the "No More Tears (Enough is Enough)" duet with Barbra Streisand which was co-produced by Gary Klein of The Entertainment Company.
Link Information: "No More Tears (Enough is Enough)" duet with Barbra Streisand which was co-produced by Gary Klein Answer: 2000000
A:
How many copies of the duet produced by Gary Klein were sold?