Gene's votes to Total votes
= Gene's votes: Total votes - 15
Since you did not provide the number of votes, I will give an example.
55 people voted for Dee, 45 people voted for Gene. This means the Total votes cast was 100.
The ratio of Dee's votes to total votes is: 55:100 ⇒ 11:20 when reduced
The ratio of Gene's votes to total votes is: 45:100 ⇒ 9:20 when reduced
If 15 people who voted for Dee did not vote, then the total number of voters is 85 so the ratios change as follows:
Dee: (55-15):(100-15) ⇒ 40:85 ⇒ 8:17 when reduced
Gene: (45-0):(100-15) ⇒ 45:85 ⇒ 9:17 when reduced