Professor Goodheart gives 3 midterm exams. He drops the lowest score and gives each student her average score on the other two exams. Polly Sigh is taking his course and has a 60 on her first exam. Let x2 be her score on the second exam and x3 be her score on the third exam. If we draw her indifference curves for scores on the second and third exams with x2 represented by the horizontal axis and x3 represented by the vertical axis, then what is her indifference curve through the point (x2, x3) = (50, 70)