First, we need to determine the overall number of portions. To do this, we begin by performing 20*2= <<20*2=40>>40 portions after the first halving.
Next, we take this portion number and double it again, performing 40*2=<<40*2=80>>80 portions after the second halving.
Lastly, we divide this portion number by the number of portions each person will be served, performing 80/8=<<80/8=10>>10 people served.
#### 10