Answer:
you basically do the same things just backwards
Step-by-step explanation:
for example 9+9=18 well to double check your work all you do is flip to equation 18-9=9
Answer:
Step-by-step explanation: what triangle?
Answer:

Step-by-step explanation:
The additive number of any number is the number when added to the number gives a result of zero.
So, if we add 10 to -10 we get a result of zero.
=> -10+10
=> Zero