Question from Kerry:

The answer key gives 5 statement answers, but the proof only has 4 statements. I don’t know which of the 5 in the answer key is extraneous. Assuming the last one should be dropped, the answer in the key for statement 2 is subtraction, but I think it is addition. There is no subtraction for statement 2. Could you clarify/verify the 4 correct reasons for the 4 steps?

Answer from Dr. Callahan:

This should be

1) Given2) Addition3) Given4) Substitution

The answer key you have is a reprint from the original (oddly the original has the correct answers) and is new. We will document any errors at askdrcallahan.com/support.