So 1.25 times 15, (because she uses 1.25 ounces every time and she used it 15 times), so THAT answer would be 18.75 fluid ounces, and now you subtract 35.4 - 18.75, (you subtract da amount of fluid ounces she used from da total amount of fluid ounces ), and your answer would be 16.65. I will leave da rounding up to you. I hope I helped! :-)