Final answer:
Using the commutative property of addition, the expression (1.23+5.76)+5.99 can be rewritten as 1.23 + (5.76+5.99). This property states that the order in which numbers are added does not change the sum.
Step-by-step explanation:
The question asks us to use the commutative property of addition exactly once to rewrite the expression (1.23+5.76)+5.99. The commutative property of addition states that the order in which numbers are added does not change the sum. So, we can rearrange the numbers in the expression to get the same sum. Therefore, we can rewrite the expression as 1.23 + (5.76+5.99).
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