Final answer:
The expression '3 decreased by the quotient of 9 and a number' is represented as 3 - (9/x), where x is the number we're dividing 9 by.
Step-by-step explanation:
The phrase '3 decreased by the quotient of 9 and a number' represents an algebraic expression that can be written as 3 - (9/x), where x is the unknown number. When you see the term 'quotient', it refers to the result of division. So, you first divide 9 by the number, which is represented as 9/x, and then decrease 3 by that result.
To put it simply, if we consider x to be 3 for example, the quotient of 9 and 3 would be 3, and then 3 decreased by 3 is 0. That's just an example with x being 3, but the initial expression will change depending on the actual value of x.