Answer:
Step-by-step explanation:
The properties of addition and multiplication allow you to rearrange and/or regroup the components of a sum or a product. That is the point of this exercise.
(2·8)·7 = 2·(8·7) . . . . parentheses have moved: associative property
2 + 7 + 8 = 8 + 2 + 7 . . . . order is rearranged: commutative property
5·3·12 = 12·5·3 . . . . . order is rearranged: commutative property
(3 +5) +12 = 3 +(5 +12) . . . . parentheses have moved: associative property
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Additional comment
Whenever you're in doubt about the equivalence of numerical expressions, you can use your calculator to evaluate them. They will give the same result if they are equivalent. (You need a good scientific or graphing calculator that uses parentheses for this. Some seriously good calculators are available as low-cost phone apps.)
The Google search box also serves as input to the Google calculator. You can use an asterisk (*) for multiplication.
