A​ student's course grade is based on one midterm that counts as 20​% of his final​ grade, one class project that counts as 25​% of his final​ grade, a set of homework assignments that counts as 45​%...

A​ student's course grade is based on one midterm that counts as

of his final​ grade, one class project that counts as

of his final​ grade, a set of homework assignments that counts as

of his final​ grade, and a final exam that counts as

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.