Liu Li and Li Yun measured the shadow lengths of a big tree and a small tree at the same time, and they were 9m and 2m respectively. They also measured that the actual height of the small tree is 0.8m. How tall is the big tree?
刘丽和李芸同时测量大树和一棵小树的影长，分别是9m和2m．她们又测得小树实际高0.8m，大树有多高？
<gadget id="calculator">0.8 / 2</gadget>
<output>0.4</output>

<gadget id="calculator">0.4 * 9</gadget>
<output>3.6</output>

<result>3.6</result>