Final answer:
By setting up a proportion based on the given information, we determine that Yolanda's club must have a total of 25 members to meet the 80% attendance requirement for voting with at least 20 members present.
Step-by-step explanation:
To determine the total number of members in Yolanda's club, given that 80% of the members must be present for a vote and that at least 20 members must be present, we set up a proportion. Since 80% represents the fraction of the total members, we can represent the total number of members by a variable, let's use x. The proportion would then be 80% of x (or 0.8x) equals 20 members. The equation to solve for x would be:
0.8x = 20
To solve for x, divide both sides of the equation by 0.8:
x = 20 / 0.8
x = 25
Therefore, to have a minimum of 20 members present for a vote, with the requirement that 80% of members must be present, the club must have a total of 25 members.