Marcus gets the following course grades in each of his subjects for the year. A 3 column table with 4 rows. Column 1 is labeled Subject with entries English Language Arts, Math, Science, Social Studies. Column 2 is labeled Letter grade with entries A, A plus, A minus, B. Column 3 is labeled 4.0 scale with entries 3.8, 4.0, 3.6, 3.0. What is the first step that Marcus should take to calculate his overall percentage GPA for the year? add up all the points divide the sum by the total number of points round to the nearest tenth change the decimal into a percentage