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.