The way this exercise is supposed to be done is:

• add left+middle block from the bottom row, and write the result to left block of the middle row
• add middle+right block of the bottom row and write the result to the right block of the middle row
• add left+right block of the middle row and write the result to the top row.

The idea is that the two supporting blocks below have the same “weight” as the block directly above.

I don’t know if this page was AI generated, but its clearly wrong.