The first thing we must do for this case is to see how many representatives from each country attended.
We have then:
Argentines = (1/6) * (120) = 20
Chileans = (1/5) * (120) = 24
Bolivians = (1/4) * (120) = 30
Venezuelans = (1/4) * (120) = 30
Adding we have:
20 + 24 + 30 + 30 = 104
Therefore the number of Americans is:
120-104 = 16
Answer:
16 Americans attended the wind energy conference