The alarm clock points to 8:15, the watch points to 8:31, the alarm clock is 1 minute ahead of the standard time every 3 hours, and the watch is 5 minutes behind the standard time every 7 hours. How many hours later does the alarm clock and time point to the same time?
闹钟指向8点15时，手表指向8点31，闹钟比标准时间每3小时快1分钟，手表比标准时间每7小时慢5分钟．几小时后，闹钟和时间指向同一时间？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">(1/3) + (5/7)</gadget>
<output>22/21 = around 1.047619</output>

<gadget id="calculator">16 / (22/21)</gadget>
<output>168/11 = around 15.272727</output>

<result>168/11 = around 15.272727</result>