Answer:
9. 23
10. D
Explanation:
9.
In order to make the equation true, the blank must contain 23.
That statement, however, is an example of the commutative property of addition. The symmetric property says if a = b, then b = a.
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10.
Your calculator can tell you which expressions are equivalent to 25·18. Clearly, the sum in choice D is not a product that will be equivalent.