Hello.
The reaction is:
[tex]\mathsf{5 Fe_{3}O_{2} + 15 CO \to 15 CO_{2}}[/tex]
[tex]\mathsf{Ratio = \dfrac{15}{15} = 1}[/tex]
The mole ration of carbon dioxide to carbon monoxide is 1, as for every mole of carbon monoxide, there is one mole of carbon dioxide.
Hope I helped.