Respuesta :

Answer:

9+x<12

Step-by-step explanation:

add 9 to an unknown number.

9+x

use the < less than symbol (instead of an equal sign) and write 12.

Answer:

x + 9  < 12

Step-by-step explanation:

Let the unknown number = x

Sum of 9  and x  :  x + 9

x + 9  < 12