Solving the operations:
[tex]n=\frac{80000}{104000+154000+123000+80000}=\frac{80000}{461000}=\text{0}.174[/tex]Now we multiply by 100 to convert to percentage:
[tex]\text{0}.174\times100=17.4\text{ percent}[/tex]Therefore, oct-dec sales are 17.4% of the total sales.