Assuming her weight loss is going to happen through nutrition alone. This question can be answered if we make apparent a few points. One pound is equal to 3500kcals. Jackie needs to lose 15lbs in 3 months. Therefore, she really needs to lose 52,500kcals (15lbs x3500kcals). In 3 months this equates to a caloric deficit of approx 584kcals/day (52,500kcals divided by 90days). So in order to reach her target goals she’s needs to be in a caloric deficit of 584kcals a day for 3 months from her current caloric intake that permits the maintenance of her body weight.