From the question, 240 people are going to a charity event and 3/5 of the guests have ordered chicken for their meals. This means (3/5 × 240) = 144 people ordered chicken. Since 144 people have ordered, the number of remain people left will be:
= 240 - 144
= 96 people.
Out of the remaining guests which is 96, 12.5% have ordered gluten free meals. This means (12.5% × 96) = 12 ordered gluten free meals.
The people who haven't ordered their meals yet will be: