Answer :
Marjorie's mistake was that she multiplied 3x wrong. If x=5, then 3x should equal 15, not 35 because 5*3=15.
Hello!
She has multiplied 3x wrong. If x=5, then 3x should equal 15, not 35. But 7 ⋅ 5 = 35 but that is irrelevant. So in total she multiplied incorrectly.
I hope it help!