Ada's daily electric consumption is 12 kilowatts per hour. She is planning to add a device that will consume 2 kilowatts per hour a day. If a kilowatt per hour is $1.50, how much is the difference between Ada's weekly electric bill before and after she adds the new device?
Ada's weekly electric consumption before adding the new device is 12 x 7 = 
<gadget id="calculator">12*7</gadget>
<output>84</output>
84.
So, her weekly electric bill is 84 x $1.50 = $
<gadget id="calculator">84*1.5</gadget>
<output>126</output>
126.
Ada's daily electric consumption after adding the new device is 12 + 2 = 
<gadget id="calculator">12+2</gadget>
<output>14</output>
14.
So her weekly electric consumption after adding the new device is 14 x 7= 
<gadget id="calculator">14*7</gadget>
<output>98</output>
98 kilowatts per hour.
Ada's new electric bill per week will be 98 x $1.50 = $
<gadget id="calculator">98*1.5</gadget>
<output>147</output>
147.
Therefore, the difference between the bill before and after she adds the new device is $147 - $126 = $
<gadget id="calculator">147-126</gadget>
<output>21</output>
21.

<result>21</result>