Tommy understands that two equal quantities remain equal even though the form or appearance is rearranged. This shows that Tommy used to be in the stage of development and has transitioned to the stage of development.

Preoperational stage; concrete operational.

Explanation:

The concrete operational stage of cognitive development is one of the the four stages of cognitive development proposed by Piagets in his theory. concrete operational stages of cognitive development occurs between the ages of seven(7) to eleven (11) years old and it is the third stage of cognitive development. In this stage of cognitive development that is concrete operational stage is a stage where the thinking of children becomes more concrete. Before the concrete operational stage we have the Preoperational stage which occurs between the ages of two(2) to seven(7) years old which means that Tommy was in this stage before his transitioning into concrete operational stage of cognitive development.

the answer is 12 hope it