The bus travels 900 kilometers in 15 hours. The passenger car travels 1200 kilometers in 15 hours. How much more miles per hour can a small passenger car travel than a large passenger car?
大客车15小时行900千米．小客车15小时行1200千米．小客车比大客车每小时多行多少千米？
<gadget id="calculator">1_200 / 15</gadget>
<output>80</output>

<gadget id="calculator">900 / 15</gadget>
<output>60</output>

<gadget id="calculator">80 - 60</gadget>
<output>20</output>

<result>20</result>