1. **State the problem:** The carpenter builds 11 bookshelves and 25 tables. Each bookshelf requires 1 box of screws, 4 pieces of 2 x 4's, and 4 sheets of plywood. Each table requires 2 boxes of screws, 2 pieces of 2 x 4's, and 1 sheet of plywood. The carpenter starts with 80 boxes of screws, 105 pieces of 2 x 4's, and 80 sheets of plywood. We need to find how many materials are leftover after building 11 shelves and 25 tables. 2. **Write the formulas for total materials used:** - Boxes of screws used: $$1 \times 11 + 2 \times 25 = 11 + 50 = 61$$ - 2 x 4's used: $$4 \times 11 + 2 \times 25 = 44 + 50 = 94$$ - Sheets of plywood used: $$4 \times 11 + 1 \times 25 = 44 + 25 = 69$$ 3. **Calculate leftover materials:** - Boxes of screws leftover: $$80 - 61 = 19$$ - 2 x 4's leftover: $$105 - 94 = 11$$ - Sheets of plywood leftover: $$80 - 69 = 11$$ 4. **Answer:** The carpenter has 19 boxes of screws, 11 pieces of 2 x 4's, and 11 sheets of plywood leftover.