Two cities, A and B, are several kilometers apart. A train of passenger cars and a train of trucks depart from the two cities at the same time. They meet after 3 hours. When they meet, the bus travels 60 kilometers longer than the truck. The ratio of the speed of the truck to the bus is known to be At 9:11, how many kilometers per hour does the truck travel on average?
甲、乙两个城市相距若干千米，一列客车与一列货车同时从两个城市相对开出，3小时后相遇，相遇时客车比货车多行60千米，已知货车与客车速度的比是9：11，货车平均每小时行多少千米？
<gadget id="calculator">11 + 9</gadget>
<output>20</output>

<gadget id="calculator">11 / 20</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(11/20) - (9/20)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">60 / (1/10)</gadget>
<output>600</output>

<gadget id="calculator">(9/20) / 3</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">600 * (3/20)</gadget>
<output>90</output>

<result>90</result>