The first parenthesis is (y + 12) and the second parenthesis is ( - y - 12 ).
<u>These two has to be equal in order for her to combine terms and simplify further.</u>
<em><u>For them to be equal, she </u></em><em><u>SHOULD HAVE</u></em><em><u> factored out a -7 from the second group of factors so the term inside the 2nd parenthesis would have been ( - y - 12 ) thus making the factoring and simplification possible!</u></em>