On a certain road, there is an intersection every 900 meters, and the signal lights at the intersection are set according to the cycle of green light for 30 seconds, yellow light for 5 seconds, and red light for 25 seconds. A car passes through the first intersection with a green light, how many kilometers does the car need to travel per hour to pass through each intersection with a green light?
某条道路上，每隔900米有一个路口，路口的信号灯都是按绿灯30秒，黄灯5秒，红灯25秒的周期设置．一辆汽车通过第一个路口时是绿灯，要想通过每个路口都是绿灯，这辆汽车每小时需行多少千米．
<gadget id="calculator">30 + 5 + 25</gadget>
<output>60</output>

<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">0.9 / (1/60)</gadget>
<output>54</output>

<result>54</result>