Answer: Eli read 3 historical fiction books , 7 biographies and 1 mystery book.
Explanation:
Let x be the number of historical fiction books Eli read.
Then, Number of biographies he read = x+4
Number of mysteries he read = x-2
If he read a total of eleven books during the semester , then we have the following equation :
(Subtract 2 from both sides )
(Divide both sides by 3)
Therefore , Number of historical fiction books Eli read = 3
Number of biographies he read = 3+4=7
Number of mysteries he read =3-2=1
Hence, Eli read 3 historical fiction books , 7 biographies and 1 mystery book.