Xiao Ming travels from home to school, if the speed is 150 meters per minute, he will arrive at school at 7:50; if the speed is 200 meters per minute, he will arrive at school at 7:45, Xiao Ming wants to arrive at school at 7:40 , at what speed should he advance?
小明从家到学校，如果以每分钟150米的速度，他将于7：50到校；如果以每分钟200米的速度，他将于7：45到校，小明想在7：40到校，他该以怎样的速度前进？
<gadget id="calculator">200 - 150</gadget>
<output>50</output>

<gadget id="calculator">5 / 50</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">200 * (1/10)</gadget>
<output>20</output>

<gadget id="calculator">20 - 10</gadget>
<output>10</output>

<gadget id="calculator">20 / 10</gadget>
<output>2</output>

<gadget id="calculator">150 * 2</gadget>
<output>300</output>

<result>300</result>