the answer is 88.8% how i got it is by:
30-18= 12 which is the number of member that had an average of 84
then multiply 12 times 84 = 1008 (keep this number)
last you multiply 18 by 92 which equals 1656
add 1008 and 1656 together and get 2664.
divide 2664 / 30 and you get the average of 88.8
