At 4:00 p.m., Xiao Ming measured the shadow of a building to be 30 meters long, and at the same time, he measured the shadow of a nearby tree with a height of 2 meters to be 3 meters long. How many meters high is this building?
下午4点，小明量得一幢大楼的影子长30米，同时它量得附近2米高的小树的影子长3米，这幢大楼有多少米高？
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

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

<result>20</result>