At one point in the semester, sarah has the following grades. exam 1 78 my lab 82% homework 4, 5, 0, 2 sarah needs to estimate her course grade. she defines the following variables. x = my lab percent y = homework percent z = exam percent u = estimated course percent as described in the syllabus, exams count for 5/6 of the grade, my lab for 1/12 of the grade, and homework for 1/12. she uses these values to create the equation u = 1 12 x+ 1 12 y+ 5 6 z estimate sarah’s course grade, and round to the nearest tenth of a percent.