The associative property regroups values by changing the location of parentheses. If you notice, the order of the values is not changed. Both sides have a x b x c, only the parentheses have been moved. Moving the parentheses changes the progression of what is multiplied (whatever is in the parentheses is multiplied together first) but doesn't change the final answer.
The associative property of multiplication (or addition) shows that the order the numbers are multiplied it irrelevant, more specifically in the manners of parentheses.
So, the answer is A, which can also be seen in that substituting a as 5, b as 3, and c as 6 gives us the first example.
Start by moving the decimal place in the number until you have a coefficient between 1 and 10. The number of places to the left that you had to move the decimal point is the exponent. so for example, 0.000345 would be 3.45(10)^4
