Answer:

The required expression is 12+frac{9}{y}.

Step-by-step explanation:

Consider the provided phrase.

The sum of 12 and the quotient of 9 and a number

Let the number is y and the quotient of 9 and a number can be written as:

frac{9}{y}

Thus, the sum of 12 and the quotient of 9 and a number can be written as:

12+frac{9}{y}

Hence, the required expression is 12+frac{9}{y}.