ANSWER
[tex]\frac{43}{72}[/tex]EXPLANATION
First, we have to find the total sum of 7/8 and 5/9.
That is:
[tex]\begin{gathered} \frac{7}{8}+\frac{5}{9} \\ \frac{(9\cdot7+8\cdot5)}{72} \\ \Rightarrow\frac{63+40}{72} \\ \Rightarrow\frac{103}{72} \end{gathered}[/tex]Now, we subtract 5/6 from that.
That is:
[tex]\begin{gathered} \frac{103}{72}-\frac{5}{6} \\ \frac{103-(5\cdot12)}{72} \\ \frac{103-60}{72} \\ \Rightarrow\frac{43}{72} \end{gathered}[/tex]That is the answer.