Boat B sailed along the river for 2 hours, traveled 120 kilometers, and returned to the original place in 4 hours. It took 3 hours for Ship A to sail along the same section of waterway. How many hours longer did it take for Ship A to return to the original place than when it went there?
乙船顺水航行2小时，行了120千米，返回原地用了4小时．甲船顺水航行同一段水路，用了3小时．则甲船返回原地比去时多用了几小时？
<gadget id="calculator">120 / 3</gadget>
<output>40</output>

<gadget id="calculator">60 - 30</gadget>
<output>30</output>

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

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

<gadget id="calculator">40 - 30</gadget>
<output>10</output>

<gadget id="calculator">120 / 10</gadget>
<output>12</output>

<gadget id="calculator">12 - 3</gadget>
<output>9</output>

<result>9</result>