A family of 2 parents and 2 children is waiting in line…

A family of 2 parents and 2 children is waiting in line to order at a fast-food restaurant. Joey, the younger child, has a tendency to cause mischief when he is not watched carefully. Because of this, the father wants to keep Joey ahead of him in line at all times. How many different ways can the family arrange themselves in line, such that the father is able to watch Joey?

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · dev #176