Answer:
Associative property of addition
Step-by-step explanation:
The associative property of addition is as follows :
a+(b+c) = (a+b)+c
We have,
a = 8, b = 9 and c = 3
So,
Using above property,
(8+9)+3 = 8+(9+3)
20 = 20
Hence, this is the required solution.
