Mingming walks from place A to place B. He walks for 20 minutes. His speed is 70 m/min. When he returns, he rides a bicycle and it only takes 8 minutes. What is the speed of Mingming when he returns?
明明从甲地到乙地去时步行，走了20分钟，他的速度是70米/分，返回时骑自行车，只用了8分钟，明明返回时的速度是多少？
<gadget id="calculator">20 / 8</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">70 * (5/2)</gadget>
<output>175</output>

<result>175</result>