To write the given statement algebraically using $x$ as the unknown:

The statement is:
"I think of a number, multiply it by 4, and subtract 9 from the result."

This can be written algebraically as:

$4x - 9$

Let me know if you have questions or would like additional help.

Here are some related questions for you to practice:

1. How would you write "Multiply a number by 3 and then add 5" algebraically?
2. How would you represent "Subtract 7 from a number and then divide by 2"?
3. If "I think of a number, square it, and then subtract 4," what would the algebraic expression look like?
4. How can you express "Double a number and add 12" in algebraic form?
5. What algebraic expression would represent "Half a number, subtract 2, and multiply the result by 3"?

Tip: Always follow the sequence of operations mentioned in the problem when converting a statement to algebraic form.