A motorcycle and a bicycle set off from two places 290 kilometers apart at the same time and head toward each other. The speed of the motorcycle is 55 kilometers per hour. The chain of the bicycle fell off on the way, and it took half an hour to repair it. As a result, the motorcycle met the bicycle after traveling for 4 hours. Find the speed of the bicycle.
一辆摩托车和一辆自行车分别从相距290千米的两地同时出发，相向而行．摩托车的速度为每小时55千米，自行车在中途掉了车链条，修理了半小时，结果摩托车行了4小时和自行车相遇，求自行车的速度．
<gadget id="calculator">55 * 4</gadget>
<output>220</output>

<gadget id="calculator">290 - 220</gadget>
<output>70</output>

<gadget id="calculator">4 - 0.5</gadget>
<output>3.5</output>

<gadget id="calculator">70 / 3.5</gadget>
<output>20</output>

<result>20</result>