The distance between A and B is 120 kilometers. The fast and slow cars are traveling towards each other from A and B at the same time. After 40 minutes, they meet each other. After the meeting, the two cars continue to move forward at the same speed. How many kilometers is the time express train from B?
甲、乙两地相距120千米，快慢两车同时分别从甲、乙两地相向而行，经过40分钟相遇，相遇后两车继续以原速前进，又经过15分钟慢车到中点，此时快车距离乙地还有多少千米？
<gadget id="calculator">120 / 2</gadget>
<output>60</output>

<gadget id="calculator">120 / 60</gadget>
<output>2</output>

<gadget id="calculator">2 * 15</gadget>
<output>30</output>

<gadget id="calculator">60 - 30</gadget>
<output>30</output>

<result>30</result>