半夏如烟

88.4 divide 100 then times 4 = 3.536
3.536 is your average GPA for your sophomore year
Usually, the school will take care of your grade conversion.
In US, everything is based on 4.0 scale.

For regular classes
A=4.0
B=3.0
C=2.0
D=1.0
F=0.0

AP courses have a grade rise, but you are expected to get a grade of C or higher in AP courses.
A=5.0
B=4.0
C=3.0
D=1.0
F=0.0