Please read the following and provide an accurate position versus time graph.
Susan enters a classroom, sees a seat 40 m directly ahead, and begins walking toward it at a constant leisurely pace, covering the first 10 m in 10 seconds. But then Susan notices that Ella is heading toward the same seat, so Susan walks more quickly to cover the remaining 30 m in another 10 seconds, beating Ella to the seat. Susan stands next to the seat for 10 seconds to remove her backpack.