Well, if every item is divided into equal sets with no left over items I believe the correct answer is 60 children. Each set will contain 2 caps, 3 keychains and 4 bracelets with nothing left over. You can try other numbers but pretty sure you will still have things left over.
2x60 = 120
3x60 = 180
4x60 = 240
120/180/240
