It looks like your question is incomplete or fragmented. However, I think you might be asking something like: "If 3 of a certain number is 12, what is the number?" If that's correct, here's how to solve it:
Problem
If 3 times a certain number equals 12, find the number.
Solution
Let the certain number be xxx. Given:
3×x=123\times x=123×x=12
To find xxx, divide both sides by 3:
x=123=4x=\frac{12}{3}=4x=312=4
Answer
The number is 4. If you meant something else, please clarify!
