The distance between Zhou Yong's house and Li Gang's house is 600 meters. They started from their own house at the same time, walked towards each other, and met after 4 minutes. Zhou Yong walked 72 meters per minute. How many meters does Li Gang walk per minute? (solution by equation)
周永家和李刚家相距600米，他们同时从自己家出发，相向而行，经过4分钟相遇．周勇每分钟走72米．李刚每分钟走多少米？(用方程解)
<gadget id="calculator">72 * 4</gadget>
<output>288</output>

<gadget id="calculator">600 - 288</gadget>
<output>312</output>

<gadget id="calculator">312 / 4</gadget>
<output>78</output>

<result>78</result>