Answer: Associative property of addition
Step-by-step explanation: The statement (6 + 2) + 1 = 6 + (2 + 1) represents the associative property of addition. Notice that the addends or the numbers were adding are the same on both sides of the equals sign 6 + 2 + 1 but on the left side, 6 and 2 are grouped together and on the right side, 2 and 1 are grouped together.
The associative property of addition says that when we are adding more than two numbers, the grouping of the addends does not affect the sum.
Here, notice that 6 + 2 is 8 and 8 + 1 is 9. On the right side, the order of operations tells us to begin inside the parentheses so we have 2 + 1 which is 3 and 6 + 3 is also 9.
In general terms, we can write the associative property of addition as
(a + b) + c = a + (b + c) where a, b, and c are variables that can represent any number.