To find the surface area of the package, we need to calculate the areas of the three rectangular faces (lateral faces) and the two triangular faces.
The area of the rectangular faces can be found by multiplying the length and height of each face. Since the height of the package is 20 centimeters, the area of each rectangular face is 6 cm * 20 cm = 120 square centimeters. Since there are three rectangular faces, the total area of the rectangular faces is 3 * 120 square centimeters = 360 square centimeters.
The area of each triangular face can be found using the formula for the area of a triangle, which is (base * height) / 2. The base of each triangular face is 6 centimeters, and the height is 10 centimeters. Therefore, the area of each triangular face is (6 cm * 10 cm) / 2 = 30 square centimeters. Since there are two triangular faces, the total area of the triangular faces is 2 * 30 square centimeters = 60 square centimeters.
Finally, we add the area of the rectangular faces and the area of the triangular faces to find the total surface area of the package: 360 square centimeters + 60 square centimeters = 420 square centimeters.
Therefore, the surface area of the package is 420 square centimeters.