An athlete participated in a long-distance running competition. It took a total of 40 minutes from seeing the first drinking water station to seeing the third drinking water station. It is known that every two drinking water stations are 5 kilometers apart from the starting point to the finishing point (there are both ends), and it took him 3 hours to run the full length. How many kilometers is the distance of this race?
一名运动员参加长跑比赛，从看见第一个饮水站到看见第3个饮水站，共花了40分钟．已知从起点到终点每两个饮水站间隔为5千米(两端都有)，他跑完全长共花了3小时，这次比赛的赛程是多少千米？
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">60 / 20</gadget>
<output>3</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">5 * 9</gadget>
<output>45</output>

<result>45</result>