Xiao Ming and Xiao Gang set off from school to Xiaoxiao's home. Xiao Ming started first at a speed of 40 meters per minute. After 2 minutes, Xiao Gang started at a speed of 44 meters per minute. Question: How many minutes later can Xiao Gang catch up with Xiao Ming? (Solution of column equation)
小明和小刚从学校出发去笑笑家，小明以每分40米的速度先出发，2分后，小刚以每分44米的速度后出发．问：几分后小刚能追上小明？(列方程解)
<gadget id="calculator">40 * 2</gadget>
<output>80</output>

<gadget id="calculator">44 - 40</gadget>
<output>4</output>

<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<result>20</result>