Xiao Gang is 0.75 kilometers behind Xiao Ming. They both come to school at the same time. Xiao Gang walks 250 meters per minute, and Xiao Ming walks 150 meters per minute. How long does it take for Xiao Gang to catch up with Xiao Ming?
小刚在小明后面0.75千米，两人同时来学校，小刚每分钟走250米，小明每分钟150米，小刚多少时间追上小明？
<gadget id="calculator">0.75 * 1_000</gadget>
<output>750</output>

<gadget id="calculator">250 - 150</gadget>
<output>100</output>

<gadget id="calculator">750 / 100</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>