df3
                           Very interested  Somewhat interested Not interested
Data Analysis/Statistics    1688             444                 60
Machine Learning            1629             477                 74
Data Visualization          1340             734                102
Big Data(Spark/Hadoop)      1332             729                127
Deep Learning               1263             770                136
Data Journalism             429             1081                610

totals
Data Analysis/Statistics    2192
Machine Learning            2180
Data Visualization          2176
Big Data(Spark/Hadoop)      2188
Deep Learning               2169
Data Journalism             2120

df4 = df3.apply(lambda x, totals: x/totals)

TypeError: ("<lambda>() missing 1 required positional argument: 'totals'", 'occurred at index Very interested')