The distance between two stations A and B is 660 kilometers. Two trains depart from the two stations at the same time. After 4 hours, the two trains meet. Car A travels 90 kilometers per hour. How many kilometers per hour does train B travel? (solution by equation)
甲乙两站相距660千米，两列火车同时从两站相对开出，经过4小时两列火车相遇，甲车每小时行90千米，乙车每小时行多少千米？(用方程解)
<gadget id="calculator">90 * 4</gadget>
<output>360</output>

<gadget id="calculator">660 - 360</gadget>
<output>300</output>

<gadget id="calculator">300 / 4</gadget>
<output>75</output>

<result>75</result>