It takes Fangfang 30 seconds to go from the 1st floor to the 3rd floor, so calculate how many seconds it will take her to go from the 2nd floor to the 6th floor.
芳芳从1楼到3楼要用30秒，这样计算她从2楼到6楼要用多少秒．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">6 - 2</gadget>
<output>4</output>

<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<result>60</result>