It took Xiaowei 15 minutes to go to school by bicycle, and he went back the same way when he got home from school. The speed increased (1/4), how many minutes did it take him to go home?
小伟上学骑车用了15分钟，放学回家还顺原路返回，速度加快了(1/4)，他回家用了多少分钟．
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(1/15) * (5/4)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / (1/12)</gadget>
<output>12</output>

<result>12</result>