Can you subtract two rational numbers and get an irrational number?

Do you mean can we subtract one rational number from another rational number and get an irrational number as the difference? I'm not a mathematician, but I suspect strongly the answer is no. Wouldn't this imply that we can sometimes add a rational number to an irrational one, and get a rational number as a sum? That doesn't seem possible.

Ans 2.

It isn't possible. Proof :-

Given two rational numbers, multiply the two denominators.

Express each rational in terms of the common multiple.

Algebraically add the numerators of the new rational numbers.

Put this over the common multiple; there's the result expressed as a ratio.