Hi, first of all, what kind of porgram are you in?
You cannot retake exams in a career or a degree program, unless you failed for the first time. Retaking exams in these types of programs will result in a passing (60) grade.
Should you be in the high school program, you can retake exam for a higher grade.
Please, check your Student Handbook, which you can download logging into the Student Portal and navigate to 'Learning' > 'Documents'.