Final answer:
The commutative property of addition allows for mental computation in simplifying the given problem.
Step-by-step explanation:
The property that would allow you to use mental computation to simplify the problem 27+15+3+5 is the commutative property of addition. This property states that the order in which numbers are added does not change their sum. Therefore, you can rearrange the numbers in any order and still get the same result. In this case, you can mentally compute the sum by grouping numbers that are easier to add together, such as 27+3 and 15+5, and then adding the two results.
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