Answer: 120cm squared
Step-by-step explanation: To do this you can cut off one of the 'triangle ends' on the trapezoid and add it to the other side to make a rectangle. Since the top is 10cm, each triangle will have a base of 5cm, so the bases will be 15cm when you subtract 20-5. Then you just have 8 * 15 which is 120cm SQUARED. This may have been a little confusing so i attachecd a diagram.