Pamela is building a 2 wooden decks. Each deck needs 25 pieces of wood and each piece of wood needs 8 screws. If Pamela already have 40 screws, how many more screws does she need to buy?

360 screws

Step-by-step explanation:

First we need to determine how many screws she needs for the 2 decks

We will determine the number of screws for 1 deck

1 deck uses 25 pieces of wood

25 pieces of wood * 8 screws / piece of wood = 200

200 screws per deck

She is building 2 decks

2 * 200 = 400

400 screws for the 2 decks

She has 40 screws

400 screws she needs - 40 screws she has = 360 screws she still needs