Nineteen less than the quotient of a number and fifteen" as a mathematical expression.        

less than   means subtract

quotient is division

nineteen less than the quotient of a number and fifteen

n/15 - 19

Step-by-step explanation:

Quotient of number and 15 means

Where 'n' is the number.

Now statement "Nineteen less than the quotient of a number and fifteen" can be written as