On the first day of the new year, I followed my parents to my grandparents' house to pay New Year's greetings. Along the way, my father’s car was driving at a constant speed, about 42.5 km/h. I set off at 7 am and arrived at my grandparents’ house by 9 am. Do you know how far my house is from my grandparents’ house?
大年初一，我就跟着爸爸妈妈到爷爷奶奶家拜年．一路上，爸爸的车都是匀速行驶的，速度是大约42.5千米/时，早上7点出发，到爷爷奶奶家里，已经是9点了，你知道我家距离爷爷奶奶家有多远吗？
<gadget id="calculator">9 - 7</gadget>
<output>2</output>

<gadget id="calculator">42.5 * 2</gadget>
<output>85</output>

<result>85</result>