1. **State the problem:** Find the total area of the composite shape consisting of a rectangle and a triangle. 2. **Formula for area of rectangle:** $$\text{Area}_{\text{rectangle}} = \text{width} \times \text{height}$$ 3. **Formula for area of triangle:** $$\text{Area}_{\text{triangle}} = \frac{1}{2} \times \text{base} \times \text{height}$$ 4. **Calculate the area of the rectangle:** Given width = 10 units, height = 5 units $$\text{Area}_{\text{rectangle}} = 10 \times 5 = 50$$ 5. **Calculate the area of the triangle:** Given base = 10 units, height = 4 units $$\text{Area}_{\text{triangle}} = \frac{1}{2} \times 10 \times 4 = \frac{1}{2} \times 40 = 20$$ 6. **Calculate total area:** $$\text{Total Area} = \text{Area}_{\text{rectangle}} + \text{Area}_{\text{triangle}} = 50 + 20 = 70$$ 7. **Final answer:** The total area of the composite shape is **70 square units**.