A rope is 15 meters. Dad used 4 meters for the first time and 9 meters for the second time. How many meters is missing from this rope?
一根绳子15米，爸爸第一次用了4米，第二次用了9米，这根绳子少了多少米．
<gadget id="calculator">4 + 9</gadget>
<output>13</output>

<result>13</result>