The ratio of adults to girls to boys on a class field trip was 1:4:5. If the trip included 6 more boys than girls, how many adults were with the group?

A. 3
B. 4
C. 6
D. 8
E. 12

1 answer

adults --- x
girls ----- 4x
boys ------5x
(note x: 4x : 5x = 1 : 4 : 5)

"6 more boys than girls" ---> 5x = 4x+6
x = 6

so we had 6 adults, 24 girls, and 30 boys, (satisfying all our conditions stated)