Respuesta :

9514 1404 393

Answer:

  5

Step-by-step explanation:

The left side simplifies to ...

  2x +16

The right side simplifies to ...

  2x +21 -__

The x-terms are already equal. To make the constant terms equal, we want ...

  16 = 21 -__

The blank must be filled with the value 21-16 = 5 to make the statement true.

5 goes in the blank.