Aunt Wang came to Beijing from a certain city by train. The train travels 120 kilometers per hour, and the journey takes 15 hours. When she returns, she takes a car and travels 90 kilometers per hour. How long does it take to return?
王阿姨从某城市乘火车来北京，火车每小时行120千米，行了15小时，回去时乘汽车，每小时行90千米，回去时用多少时间？
<gadget id="calculator">15 / 90</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">120 * (1/6)</gadget>
<output>20</output>

<result>20</result>