Answer:
16 minutes
Step-by-step explanation: Because for 1 person it takes 10 minutes to be served and 18 minutes to serve 5 people, we must find a pattern. If you subtract 18-10 you get 8 minutes, which is the difference between 1 person and 5. Divide 8 minutes/4 people(the difference in people)= 2 minutes. Since it takes 18 minutes for 5 people, subtract 2 minutes to find the number of minutes for 4 people, which is 16. Hope this helps!