Answer:
Step-by-step explanation:
Add the negative terms and the positive terms in groups
So in the start you will just need to add 1st
Then when you add them in groups thats the time you subtract them
so:
(-13-17)+21=
(9+8)-5-2=
-30+21=-9
17-7=10
Do this method to solve these kinds of problems fast
(From a top 3 math contest winner when I was Gr 9)
