Question 939902
The answer is 3.


let X represent the number your looking for, and write the equation out accordingly.

3(x)+3=12   

3x+3=12
3x+3-3=12-3   subtract 3 on both sides
3x=9  now divide both sides by 3 to get x alone

3x/3=9/3     x=3

Now plug it back into the equation to see if its the answer your looking for.

(3)(3)+3=12
9+3=12
12=12