The usual conversion is
A*/A = 4.0
B = 3.7
C = 3.0
Yours would be 3.7. However, GPA coversion works awfully and most universities understand this. For example, I got A*A*A* in my A Levels and I emailed a Yale admissions officer and they said this would be ‘Off the GPA scale’ (Both the normal 4.0 scale and adjusted 5.0 scale).
So basically the conversions don’t really work.