A truck is traveling at a speed of 60 kilometers per hour, and a passenger car is 30 kilometers behind it. After 2 hours, the passenger car overtakes the truck. Find the speed of the bus.
一辆货车以每小时60千米的速度前进，一辆客车在它后面30千米，2小时后客车超过货车．求客车的速度．
<gadget id="calculator">60 * 2</gadget>
<output>120</output>

<gadget id="calculator">120 + 30</gadget>
<output>150</output>

<gadget id="calculator">150 / 2</gadget>
<output>75</output>

<result>75</result>