Obviously it took 6 minutes to walk from the first floor to the third floor. At this speed, how many minutes will it take to walk from the first floor to the sixth floor?
明明从一楼走到三楼用了6分钟，照这样的速度，从一楼走到六楼要多少分钟．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<result>15</result>