Answer:

−9

10

Step-by-step explanation:

Sana makatulong po ❤

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)