If she was going to divide by 3 to eliminate the x term's coefficient, she needed to divide all other terms by 3 and she did not. She only divided two of the three terms by 3 and left out the 6.
3x + 6 = 24
divide all terms by 3
3x/3 + 6/3= 24/3
x + 2= 8
subtract both sides by 2
x= 6
CHECK:
3x + 6 = 24
3(6) + 6= 24
18 + 6= 24
24= 24
ANSWER: She did not divide all terms by 3 when eliminating the x term's coefficient. x= 6
Hope this helps! :)