Final answer:
The question requires calculating the number of members who sang the third song in a club, but it lacks sufficient data on how many members sang the first and second songs. Therefore, a direct numerical answer cannot be provided without additional information.
Step-by-step explanation:
The question concerns a math problem that involves working with percentages and basic counting. There are 80 members in a club, and we need to determine how many members sang the third song, given the conditions that some sang the first and some others the second song. Without the specific percentages or numbers for the first and second songs, we cannot provide a numerical answer. We can only state that the number of members who sang the third song would be the total number of members minus the number of members who sang the first and second songs respectively.