To answer this you will draw a trapezoid and label the points A through D in order. See the picture I have attached. When you create triangle ACD, you have the base of the triangle as 10 and you know the total area. Using this information you can find the height. See the work in the picture. You will solve the equation to find the Height. When you know the height, then you can use the formula for area the trapezoid to find the area of this trapezoid. I have included the work for all the steps described.