During the May Day holiday, Xiaoming's family of three drove to Hangzhou to play. When we went there, my mother drove the car very slowly, 80 kilometers per hour, and drove for 5 hours. When we returned, we were eager to return home. Dad drove at a faster speed, and it took 1 hour less. What is the velocity when returning?
五一假期，小明一家三口开车去杭州游玩．去时，妈妈把车开得很慢，每小时行80千米，行驶了5小时，返回时我们归心似箭，爸爸开车的速度提高了，少用了1小时．返回时的速度是多少？
<gadget id="calculator">80 * 5</gadget>
<output>400</output>

<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">400 / 4</gadget>
<output>100</output>

<result>100</result>