At a fun fair, 2/5 of the number of boy is equal to 1/3 of the number of girls. The number of adults is 1/4 of the total number of children. Each boy spent $3, each girl spent $5 and each adult spent $8. The total amount of money spent by the girls was $1600 more than the total amount of money spent by the adults. What was the total number of adults at the fun fair?