Both lev vygotsky and jean piaget believed that

They also both accept the idea that development is driven by conflicts in thinking, and they both acknowledge the existence of egocentric speech. Vygotsky believed that the child is a social being, and cognitive development is led by social interactions. Hope this helps

They both accept the idea that development is driven by conflicts in thinking, and they both acknowledge the existence of egocentric speech. 

The answers is gonna be 20