Respuesta :

Answer:

9

Step-by-step explanation:

You can fill the blank with 9

3x+2.5=12x-9x+9

12x-9x is 3x

so the equation is 3x+2.5=3x+9

Subtract 3x on both sides:

2.5=9

Which is not true; thus no solution

Hope this helps!
9 the
Reason is that I trust the guy that said the answer before me