b = a+4
a = b/2 + 5
a = (a+4)/2 + 5
2a = a+14
a = 14
b = 18
At a certain dance class, each student must pick exactly one partner. Each pair of dancers must consist of one advanced student and one beginner student. At first, after everyone pairs up, there are 4 extra beginner students. Then, after half of the beginner students have left, there are 5 extra advanced students. How many advanced students are in the class?
1 answer