is GPA calculated with all the subjects? or should you calculate your GPA for each subject separately?

Answer 1

Gpa if unexplained should be a weighted average calculation of all classes. Ex: English 4 units B, Math 5 units A, PE 1 unit C.
3*4+5*4+1*2=34 divided by total units 10 equals 3.4 gpa.

You can manipulate to look better if you explain. GPA in major or gpa over past 3 years, etc. Many colleges exclude freshmen grades and pe.

Answer 2

It is calculated with all subjects. However, people with low GPAs who do well in their major often put their GPA in Major on their resumes.