Brother and sister go to school at the same time. The elder brother walks 90 meters per minute, and the younger sister 60 meters. I went to my sister and asked the distance between home and school. Use two methods of solving equations and calculating formulas.
兄妹同时上学，哥哥每分钟90米，妹妹60米，哥哥走到校门口时，发现忘了带教科书，立即原路返回家中，取上书后又往学校走，走到离学校180米的地方追上了妹妹，问家与学校的距离．使用解方程和算式两种方法．
<gadget id="calculator">180 / 90</gadget>
<output>2</output>

<gadget id="calculator">180 / 60</gadget>
<output>3</output>

<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">1 / 90</gadget>
<output>1/90 = around 0.011111</output>

<gadget id="calculator">(1/60) - (1/90)</gadget>
<output>1/180 = around 0.005556</output>

<gadget id="calculator">5 / (1/180)</gadget>
<output>900</output>

<result>900</result>