whats a real number that can be expressed as a ratio of two intergers ?
It is called a fraction, and it is one of the "rational" numbers. (So are the integers themselves.)
A real number that can be expressed as a ratio of two integers is called a rational number. To find a rational number, you need to identify any two integers and express their ratio. Here's an example:
Let's take the integers 4 and 7. To express their ratio, you simply write one number as a fraction over the other. In this case, it would be 4/7.
The resulting fraction, 4/7, is a rational number because it represents the ratio of two integers.