What is 77.8 letter grade in seneca college?

Seneca College doesn't publish a simple letter grade equivalent for numerical scores. Their grading system uses a range of percentage marks to determine the letter grade. A score of 77.8% would likely fall within the B- or B range, but the exact letter grade depends on the specific course and professor's grading rubric. You should consult your course syllabus or the professor directly to be certain.