A car and a bicycle start from two places A and B opposite at the same time. After 4 hours, the two cars meet on the way. The distance between A and B is 240 kilometers, and the car travels 45 kilometers per hour. How many kilometers per hour does the bicycle travel.
一辆汽车和一辆自行车同时从甲、乙两地相向出发，4小时后两车在途中相遇，甲、乙两地相距240千米，汽车每小时行45千米．自行车每小时行多少千米．
<gadget id="calculator">240 / 4</gadget>
<output>60</output>

<gadget id="calculator">60 - 45</gadget>
<output>15</output>

<result>15</result>