The fast troop is going to perform a mission somewhere. If it advances 30 kilometers per hour, it takes 6 hours to arrive; now it needs to arrive within 4 hours. How many kilometers must it advance at least per hour?
快速部队要去某地执行任务，如果每小时前进30千米，需要6小时到达；现在需要在4小时内到达，每小时至少要前进多少千米？
<gadget id="calculator">6 / 4</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">30 * (3/2)</gadget>
<output>45</output>

<result>45</result>