How do I create a sum row and sum column in pandas?

Or in two steps, using the .sum() function as you suggested (which might be a bit more readable as well):

import pandas as pd

df = pd.DataFrame( {"Undergraduate": {"Straight A's": 240, "Not": 3_760},"Graduate": {"Straight A's": 60, "Not": 440},})

#Total sum per column: 
df.loc['Total',:] = df.sum(axis=0)

#Total sum per row: 
df.loc[:,'Total'] = df.sum(axis=1)

Output:

              Graduate  Undergraduate  Total
Not                440           3760   4200
Straight A's        60            240    300
Total              500           4000   4500