Doug did this work to solve an equation. Did he make an error? 7x-8=-x-(12) HURRY PLZ!!!

At the newest animated movie, for every 9 children, there are 4 adults. there are a total of 39 children and adults at the movie.

Pls! does anybody know a shortcut for answering these types of questions in the future?

The clayton family’s pool has vertices at the coordinates (0, 2), (0, 5), (2, 5), (2, 6), (5, 6), (5, 1), (2, 1), and (2, 2). if each grid square has an area of 9 square feet, what is the area of the pool?