On a certain road, there is a traffic light every 900 meters. All traffic lights are green for 30 seconds, yellow for 5 seconds, and red for 25 seconds. A car encounters a green light at the first intersection. , if he wants to encounter green lights at all traffic light intersections, how many kilometers per hour should he drive at the fastest speed.
某条道路上，每隔900米有一个红绿灯，所有的红绿灯都按绿灯30秒黄灯5秒，红灯25秒的时间周期同时重复变换，一辆汽车在第一个路口处遇到绿灯后，要想在所有的红绿灯路口都遇到绿灯，则他最快该以每小时多少千米的速度行驶．
<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>