Answer: 20
Step-by-step explanation:
Given: Total students at the dinner = 100
Number of fish entrees = 40
Number of pasta entrees = 60
Number of students chose neither entree = 20
Now , Number of students chose either fish or pasta = (Total students) - (Number of students chose neither entree)
= 100-20
= 80
Now , Number of students chose either fish or pasta = (Number of fish entrees) + (Number of pasta entrees)- (Number of students chose both)
⇒ Number of students chose both = (Number of fish entrees) +(Number of pasta entrees)-(Number of students chose either fish or pasta)
= 40+60-80
= 20
Hence, the number of students were served two entrees = 20