A train travels from city A to city B. After 3 hours, it passes the midpoint of 25 kilometers. At this time, it is still 220 kilometers away from the end point. How many kilometers per hour does the train travel on average?
一列火车从甲城到乙城，3小时后超过中点25千米，此时距离终点还有220千米，这列火车平均每小时行驶多少千米？
<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<gadget id="calculator">220 + 50</gadget>
<output>270</output>

<gadget id="calculator">270 / 3</gadget>
<output>90</output>

<result>90</result>