An express train travels 90 kilometers per hour. A conductor walks from the rear to the front of the train. At the same time, a slow train travels toward each other at a speed of 72 kilometers per hour. If the conductor travels 1 meter per second, it takes 3 seconds for the slow train to pass him , how many meters is the body length of the local train?
一列快车每小时行90千米，一列车员由车尾走向车头，同时一列慢车以每小时72千米的速度相向而行，如果列车员每秒行1米，慢车经过他身旁用了3秒钟，求慢车的车身长是多少米？
<gadget id="calculator">1_000 / 60 / 60</gadget>
<output>5/18 = around 0.277778</output>

<gadget id="calculator">90 * (5/18)</gadget>
<output>25</output>

<gadget id="calculator">72 * (5/18)</gadget>
<output>20</output>

<gadget id="calculator">25 + 1 + 20</gadget>
<output>46</output>

<gadget id="calculator">46 * 3</gadget>
<output>138</output>

<result>138</result>