Assuming your fraction is 1/8 of the pie, there will be 16 guests at the party.
Step-by-step explanation:
You have to take the 1/8 and realize that each pie will be broken into 8 pieces. Since you have 2 pies you have to multiply this number by 2. This gives you 16 pieces for all 16 members that will attend the party.
Hope this helps!