-5 divided by 20 isn't an irrational number because the quotient of that problem equals -0.25. If the decimal form of a number stops or repeats, the number is rational. If the decimal does not stop and does not repeat, the number is irrational. Therefore, since -0.25 stops, it is a rational number, and not an irrational number.
Step-by-step explanation:
Sorry if the explanation isn't good, or there are some grammar mistakes. But i hope this helps :)