A passenger car travels from A to B at 75 km per hour and is expected to arrive in 3 hours. The bus broke down after driving for 1 hour, and it took 20 minutes to stop on the spot for maintenance. If the passenger car arrives at point B on time, how many kilometers should it speed up per hour in the future?
一辆客车从甲地开往乙地，每小时行驶75km，预计3小时到达．客车行驶1小时后发生了故障，就地停下维修用了20分钟．客车要准时到达乙地，以后每小时应加快多少千米．
<gadget id="calculator">75 * 3</gadget>
<output>225</output>

<gadget id="calculator">75 * 1</gadget>
<output>75</output>

<gadget id="calculator">225 - 75</gadget>
<output>150</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">3 - 1 - (1/3)</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">150 / (5/3)</gadget>
<output>90</output>

<gadget id="calculator">90 - 75</gadget>
<output>15</output>

<result>15</result>