Answer: There are 20 people who take all 3 classes.
Step-by-step explanation:
Since we have given that
Total number of sophmores = 720
Number of people who take French = 200
Number of people who take math = 300
Number of people who take Science = 350
Number of people who takes two out of three subjects = 150
Number of people who takes none = 100
So, Number of people who takes all 3 classes is given by
[tex]n(all)=n(F)+n(M)+n(S)-n(two\ subjects)+n(three\ subjects)\\\\720=200+300+350-150+x\\\\720=700+x\\\\720-700=x\\\\20=x[/tex]
Hence, there are 20 people who take all 3 classes.
