Answer: Eli read 3 historical fiction books , 7 biographies and 1 mystery book.
Step-by-step 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 :
![x+x+4+x-2=11](https://tex.z-dn.net/?f=x%2Bx%2B4%2Bx-2%3D11)
![\\\\\Rightarrow\ 3x+2=11](https://tex.z-dn.net/?f=%5C%5C%5C%5C%5CRightarrow%5C%203x%2B2%3D11)
(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.