The first thing we must do is find the percentage that has traveled outside of the United States.
For this, we make the following rule of three:
30 ---------> 100%
9 -----------> x
We clear the value of x:
x = (9/30) * (100)
x = 30%
Then, for 120 sixth graders in the school we have:
(0.30) * (120) = 36
Answer:
36 students have traveled outside of the united states
