Iphone5s can still be used for 18 hours and 40 minutes when the battery power is 80%. If the Iphone5s is now at 100% power, how many minutes have passed before the remaining 80% power.
Iphone5s在电池电量为80%的时候还可以用18小时40分钟，如果Iphone5s现在是100%的电量，那么剩下80%电量的时候过去了多少分钟．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1_120 / (4/5)</gadget>
<output>1_400</output>

<gadget id="calculator">1_400 - 1_120</gadget>
<output>280</output>

<result>280</result>