Cars A and B both start from place A to place B, which is 240 kilometers apart. Car A is 30 minutes ahead of car B and arrives 30 minutes later. If the speed ratio of car A and car B is 3:4, then car B runs every How many kilometers per hour?
A、B两车都从甲地出发去相距240千米的乙地，A车比B车先行30分钟又晚到30分钟，如果A车与B车速度比是3：4，那么B车每小时行多少千米？
<gadget id="calculator">240 / 3</gadget>
<output>80</output>

<result>80</result>