Last year, a total of 360 students attended a school camp. There were
20% more 6th graders than 5th graders, and 20% fewer 4th graders than
5th graders at the school camp. This year, 120 more students joined the
school camp. The number of 4th graders increased by 50% and the number
of 6th graders increased by 25%. What was the percent increase in the
number of 5th graders?