2007 AMC 12B Problems/Problem 10
Some boys and girls are having a car wash to raise money for a class trip to China. Initially % of the group are girls. Shortly thereafter two girls leave and two boys arrive, and then % of the group are girls. How many girls were initially in the group?
First, determine the total number of people in the group.
Now find the original number of girls:
So, there are 8 girls,