Answer:
3 3/4 i think
the two thickest books are:
[tex]\tt 1\dfrac{6}{8}~and~2[/tex]
the total:
[tex]\tt 1\dfrac{6}{8}+2=\dfrac{14}{8}+\dfrac{16}{8}=\dfrac{30}{8}=3\dfrac{6}{8}=3\dfrac{3}{4}[/tex]
