Answer:
[tex]\frac{5}{3}[/tex]
Step-by-step explanation:
let blank be O
[tex]\frac{5}{6} +O=\frac{5}{2} \\[/tex]
[tex]O=\frac{5}{2} -\frac{5}{6} =\frac{15}{6} -\frac{5}{6} =\frac{10}{6} =\frac{5}{3}[/tex]