A spring, within a certain limit, is 12.5cm long when hanging a 2kg object, and 13.5cm long when hanging a 6kg object. What is the length of a 5kg object?
一个弹簧，在一定限度内，挂2千克物体时，长12.5cm，挂6千克物体时，长13.5cm，挂5千克重物长多少．
<gadget id="calculator">13.5 - 12.5</gadget>
<output>1</output>

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

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">12.5 - (1/2)</gadget>
<output>12</output>

<gadget id="calculator">12.5 - 12</gadget>
<output>0.5</output>

<gadget id="calculator">0.5 / 2</gadget>
<output>0.25</output>

<gadget id="calculator">0.25 * 5</gadget>
<output>1.25</output>

<gadget id="calculator">1.25 + 12</gadget>
<output>13.25</output>

<result>13.25</result>