A​ student's course grade is based on one midterm that counts as ​20% of his final​ grade, one class project that counts as25 ​% of his final​ grade, a set of homework assignments that counts as ​35% of his final​ grade, and a final exam that counts as 20​% of his final grade. His midterm score is ​, his project score is ​, his homework score is ​, and his final exam score is . What is his overall final​ score? What letter grade did he earn​ (A, B,​ C, D, or​ F)? Assume that a mean of 90 or above is an​ A, a mean of at least 80 but less than 90 is a​ B, and so on. His overall final score is
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