1. The problem asks to find the area of each triangle given the base and height, then match the area to the correct answer letter. 2. The formula for the area of a triangle is $$\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}$$. 3. Important rule: Always multiply base and height first, then divide by 2. 4. Let's solve the first triangle as an example: Base = 8 in., Height = 5 in. $$\text{Area} = \frac{1}{2} \times 8 \times 5 = \frac{1}{2} \times 40 = 20 \text{ in}^2$$ 5. The area is 20 in², which corresponds to answer letter V. 6. This process is repeated for each triangle, but since the user only asked "What is this?", this is a set of geometry problems involving calculating areas of triangles and related shapes. 7. The problem also includes a question about the cost of canvas for a triangular sail and the area of a folded square napkin. 8. The main focus is on applying the triangle area formula and understanding units. Final answer for the first triangle: 20 in² (Answer V).