To complete the proof using the Commutative Property, we want to rearrange the terms in the expression \(12a + 10 + a\) such that it matches the form \(10 + a + 12a\).
Step 1 should be:
12a + 10 + a = 10 + 12a + a
This follows from the Commutative Property, which allows us to change the order of addition.
So, the response that best matches this is:
10 + 12a + a = 10 + a + 12a
Thus, after step 1, we can proceed to combine like terms in Step 2 to reach the equality shown.
The final answer for the missing step would be:
12a + 10 + a = 10 + 12a + a