Question 798226
if you mean the committee having the same ratio as the one with 30 people you have to say, but im nice so ill answer assuming thats what you meant.

12 divided by 4 = 3 so thats a 4:1 ratio 
18 divided by 4 = 4.5... sooo thats 9.5 people (thats the smallest) 
or ten people for the closest whole number answer

looks like you gotta chop somebody in half (bummer)

hope this helps

P