Arlene is showing her work in simplifying −7.9 + 8.2 − 3.4 + 2.1. Identify any errors in her work or in her reasoning. Write feedback to Arlene explaining the mistake she made and how to correct her work.

Step Work Reasoning
−7.9 + 8.2 − 3.4 + 2.1 Original problem
1 −7.9 + 8.2 + (−3.4) + 2.1 Additive inverse
2 −7.9 + (−3.4) + 8.2 + 2.1 Associative property
3 (−7.9 + (−3.4)) + (8.2 + 2.1) Commutative property
4 −11.3 + 10.3 Simplify
5 −1 Simplify

Question

Arlene is showing her work in simplifying −7.9 + 8.2 − 3.4 + 2.1. Identify any errors in her work or in her reasoning. Write feedback to Arlene explaining the mistake she made and how to correct her work.

Step	Work	Reasoning
−7.9 + 8.2 − 3.4 + 2.1	Original problem
1	−7.9 + 8.2 + (−3.4) + 2.1	Additive inverse
2	−7.9 + (−3.4) + 8.2 + 2.1	Associative property
3	(−7.9 + (−3.4)) + (8.2 + 2.1)	Commutative property
4	−11.3 + 10.3	Simplify
5	−1	Simplify

Mercury · Answer

old question but will respond so this can be closed

major hint: the actual solution is correct (-1) but she incorrectly applied one of the mathematical properties in step 3