context: Joan Mitchell (Jan White), is a 39-year-old, confident and sophisticated wife of a successful businessman named Jack Mitchell (Bill Thunhurst) who live together in a large house in suburban Pittsburgh with their 19-year-old daughter Nikki (Joedda McClain) who is a student at a local community college. But unknown to her friends, Joan is unhappy and bored with her lifestyle as a housewife which includes cleaning the house, getting her car washed, picking up her husband's dry cleaning, and grocery shopping. Jack is so obsessed with his business that he often ignores Joan and leaves on long business trips every week. Joan has been seeing a therapist about recurring dreams she's been having about her husband controlling her and keeping her locked up like a dog, as well as about a miscarriage she had many years ago.During a social party, Joan and her friends learn about a new woman in their neighborhood named Marion Hamilton (Virginia Greenwald) who practices witchcraft, they are fascinated to have an "in thing" right in their own community. Prompted by curiosity, Joan and one of her friends, Shirley (Anne Muffley), drive over to Marion's house one night for a Tarot reading where they both observe Marion's ability to deal positively with her life through her absolute faith in what she practices. Marion is also the leader of a secret woman's group which is a coven of witches in which she tells Joan a little about the group and their dealings with life in general.Joan and Shirley drive home to Joan's house where they meet Gregg (Raymond Laine), a student teacher at Nikki's college (with whom Nikki has a very casual sexual relationship). The four spend time drinking and talking about life. Gregg clearly shows an attraction to Joan, who rebuffs his flirting with her. Joan throws Gregg out out her house when he cruelly tricks the inebriated Shirley into believing that she has smoked pot, when, in fact, she has only smoked a regular cigarette.The next day, Nikki leaves without telling anybody where she's going, and soon afterward, Jack leaves for a one-week business trip, leaving Joan more alone and unhappy than ever. Joan buys a copy of the book, "To Be a Witch, A Primer", and soon practices witchcraft. She then conjures a spell to make Gregg like her, and soon the young man and older woman are engaged in an affair. Joan also has increasingly terrifying, recurring nightmares, in which she is attacked in her home by an intruder wearing a Satanic mask.Believing that she has become a witch, Joan begins to sink more deeply into her new lifestyle, until the line between fantasy and reality blurs which leads to tragedy. The police phone Joan and tell her that they have found Nikki in Buffalo, New York and that she will be coming home in three or four days. After one last sexual encounter with Gregg, Joan tells him that Nikki is coming home soon and that she doesn't want to see him again.After another terrifying nightmare involving the masked intruder, Joan accidentally shoots and kills her husband, who has unexpectedly returned home early from his business trip, after she mistakes him for the intruder.With the last link to her past lifestyle severed, Joan joins Marion's coven of witches and becomes a full-fledged witch. Cleared of her husband's death as an accident, Joan goes back to attending social parties with her friends where she quietly introduces herself as a witch. But Joan still remains lonely when people around her still do not refer to her by her first name, but either as "Mrs. Mitchell" or simply, "Jack's wife."
question: How long is Jack's business trip?
answer: one week