1. **State the problem:** We need to find the total cost of 3 pens and 2 boxes. 2. **Given information:** - Cost of 1 pen = $5x$ - Cost of 1 box = $5y$ 3. **Formula:** Total cost = (number of pens) \times (cost per pen) + (number of boxes) \times (cost per box) 4. **Calculate total cost:** $$\text{Total cost} = 3 \times 5x + 2 \times 5y$$ 5. **Simplify:** $$= 15x + 10y$$ 6. **Check answer choices:** None of the options exactly match $15x + 10y$. 7. **Factor out 5:** $$= 5(3x + 2y)$$ 8. **Interpretation:** The total cost is 5 times the quantity $(3x + 2y)$. 9. **Answer choice:** (D) $3x + 2y$ multiplied by 5 matches the total cost expression. **Final answer:** (D) $3x + 2y$