Answer:
12/(n +4)
Explanation:
"The quotient of x and y" is usually translated to mean x/y.
"The sum of a and b" is translated to mean "a+b".
Here, you want the quotient of a number (12) and a sum ("a number" and 4). It can be convenient to let "n" stand for "a number." Then the sum is (n+4), and the quotient is ...
... 12/(n +4)