Query about Question 13 from "(I'm Overwhelmed) Algebra Progress Quiz #3 (Version 2)" [7492]

https://www.gregmat.com/quizzes/quiz/im-overwhelmed-algebra-progress-quiz-3-version-2 (Question 13)

in the video explanation the answer after reducing the 2 equations was 13x. But wouldn’t it be -7x if you’re supposed to subtract the terms