Total people in party = 54
People wearing red = 18
Now the question is asking about the percentage of the people who are not wearing red.
Firstly let's find the people who are not wearing red
People not wearing red = 54 -18 = 36
Now to find the percentage we divide the number of people not wearing red by total number of people .
SO percentage of people not wearing red = 36/54 * 100 %
= 2/3 *100 = 200/3 = 66.67 %