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 :
![x+x+4+x-2=11](https://img.qammunity.org/2021/formulas/mathematics/college/m42xmq73tk8heqaq63z2e3fmkpmkbcmstd.png)
![\\\\\Rightarrow\ 3x+2=11](https://img.qammunity.org/2021/formulas/mathematics/college/rzref9326wiu3tfuj2nh2p3ffcfxteeaha.png)
(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.