Then you are adding two rational numbers with different signs! No big deal!
what is the rule in adding rational numbers
Subtraction is not commutative nor associative.
They are different in the same way that subtraction of integers is different from their addition.
There is only one type of rational number so there are no different types which you can add.
By finding their common denominator & adding the top numbers of-the fractions. : )
Whole numbers are rational numbers with a denominator of 1. The difference with general rational numbers is that the denominators are likely to be different and they must be made the same by converting the fractions into equivalent fractions with the same denominator before the addition can be done - by adding the numerators and keeping the denominator, and simplifying (if possible) the result. With whole numbers the denominators are already the same (as 1) and so the addition can be done straight away.
A rational number can be stated in the form a/b where and b are integers. Adding or multiplying such numbers always gives another number that can be expressed in this form also. So it is also rational.
when you add mixed numbers you have a whole number but adding fraction does not.
Wats are temples from South East Asia and, as far as I am aware, they do not dicatate any rules for adding rational numbers.