So if you have 3 tests each worth 23% of the grade, that leaves 31% of the grade unaccounted for. Is that homework or something? Or is it split up into smaller categories?
Basically, you multiply the grade’s weight by your score on it and add them all up. For example:
23 * 0.33 (first exam) + 23 * 0.6 (second exam) + 23 * 0.6 (final exam) + 31 * 0.6 (HW or whatever) = 53.8 (final grade)