A wire is 20 decimeters long, 10 centimeters are cut off for the first time, and 2 decimeters are cut off for the second time, how many decimeters is this wire shorter?
一根铁丝长20分米，第一次剪掉10厘米，第二次剪掉2分米，这根铁丝短了多少分米？
<gadget id="calculator">10 / 10</gadget>
<output>1</output>

<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<result>3</result>