I just want to help anyone who isn't sure if the answer is correct. Sometimes you don't want to risk using the answer and having it be wrong. But I just took my final and I got this question correct! So go rate the other answer 5 stars cause it is correct! :D
The answer for the completion exercise shown in the image attached above is: 1) Multilplication property of equality (If you multiply mEFG+mGDE=360° both sides of the equation by 1/2, you obtain 1/2(mEFG)+1/2(mGDE)=180°). 2) m∠D=1/2(mEFG) 3) m∠F=1/2(mGDE) 4)By the substitution property of equality (Because if you substitute m∠D=1/2(mEFG) and m∠F=1/2(mGDE) into 1/2(mEFG)+1/2(mGDE)=180°, you obtain: m∠D+m∠F=280°).
