Two people, A and B, are riding in the same direction on the same road. A's speed is 11 kilometers per hour, and B's speed is 14 kilometers per hour. A passes A at 11 am, and B passes B in front of A at 2 pm. The distance between A and A is 21 kilometers. How far is B from A to catch up with A?
甲乙两人骑车在同一条路上同向而行，甲时速11千米，乙时速14千米．甲上午11时经过A，乙下午2点经过A前方的B、AB相距21千米，求乙在离A多远处追上甲？
<gadget id="calculator">14 - 11</gadget>
<output>3</output>

<gadget id="calculator">11 * 3</gadget>
<output>33</output>

<gadget id="calculator">33 - 21</gadget>
<output>12</output>

<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">4 * 11</gadget>
<output>44</output>

<gadget id="calculator">44 + 33</gadget>
<output>77</output>

<result>77</result>