In a group of 400 readers who read science fiction or literacy works or both, 250 read science fiction and 230 read literacy works. How many read both science fiction and literacy works? Choose the correct choice from the following answers.
A) 70	B) 80	C) 90	D) 100	E) 110

Rationale: "consider total number of reader n ( s u l ) = 400 people who read science fiction n ( s ) = 250 people who read literacy works n ( l ) = 230 both science fiction and literacy n ( s ∩ l ) = ? n ( s u l ) = n ( s ) + n ( l ) - n ( s ∩ l ) 400 = 250 + 230 - n ( s ∩ l ) n ( s ∩ l ) = 480 - 400 n ( s ∩ l ) = 80 so people read both science fiction and literacy works are 80 answer : b"
Answer: B