Respuesta :

1/3(12 + x) is your answer

you must get the sum first  before you can one third it

hope this helps

Let

x--------> the number

we know that

1) the phrase, "the sum of 12 and a number"

represent the expression --------> [tex](12+x)[/tex]

and

2) the complete phrase, "one third the sum of 12 and a number"

represent the expression --------> [tex]\frac{1}{3}(12+x)[/tex]

therefore

the answer is

[tex]\frac{1}{3}(12+x)[/tex]