Mike took 4 courses last semester: Calculus, Physics, History, and Biology. The means and standard deviations for the final exams, and Mike's scores are given in the table below. Convert Mike's scores into z-scores.

Subject	Mean	Stand. dev.	Mike's score	Mike's z-score
Calculus	70	12	85
Physics	60	14	63.5
History	53	16	65
Biology	77	10	77

On what exam did Mike have the highest relative score?
(Enter the subject.)