The cell-phone recharges at the rate of 1 percentage-point of charge per 3 minutes. Now, the phone is at 60% charged. How long will it take to fully charge, in hours?
100-60=
<gadget id="calculator">100-60</gadget>
<output>40</output>
40 percentage points.
Then 40*3=
<gadget id="calculator">40*3</gadget>
<output>120</output>
120 minutes to fully charge.
And 120/60=
<gadget id="calculator">120/60</gadget>
<output>2</output>
2 hours.

<result>2</result>