Here are some rule : I will take 9 as first number and 4 as second number in the example
If both the number have negative sign (-) then you will add both the number and put "-" sign with the end result e.g -9-4= - 13
If one number has negative sign "-" and other has positive "+" sign then you will subtract the number and put the sign of the biggest number with the end result. E.g
As in question
First number is - 9
Second number is +4
You will subtract 9 from 4 and put the sign of bigger number with the end result. So the answer is
-9 + 4 = - 5 >>> answer
If both the number have negative sign (-) then you will add both the number and put "-" sign with the end result e.g -9-4= - 13
If one number has negative sign "-" and other has positive "+" sign then you will subtract the number and put the sign of the biggest number with the end result. E.g
As in question
First number is - 9
Second number is +4
You will subtract 9 from 4 and put the sign of bigger number with the end result. So the answer is
-9 + 4 = - 5 >>> answer