Ophelia le Jenna ba nna mo ntlong e le nngwe ya difolete. Mongwe le mongwe wa bone o na le disofa di le pedi kwa tlase ga ditilo tse a nang natso. Jenna o na le ditilo tse dintsi go menagane gararo go feta Ophelia.  Fa Ophelia a na le disofa di le 20, bala palogotlhe ya disofa le ditilo tse ba nang natso. 

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?
Fa Ophelia a na le disofa di le 20 mme a na le disofa di le pedi kwa tlase ga ditilo, o na le ditilo di le 20+2 = <<20+2=22>>22.
Jenna o na le ditilo tse dintsi go menagane gararo go feta tsa Ophelia, palogotlhe ya ditilo tse a nang natso ke 3*22 = <<3*22=66>>66
Palogotlhe ya ditilo tse Ophelia le Jenna ba nang natso ke 66+22 = <<66+22=88>>88
Ka ge Jenna le ene a na le disofa di le pedi kwa tlase ga ditilo, palogotlhe ya disofa tse a nang natso ke 66-2 = <<66-2=64>>64
Palogotlhe ya disofa tse Ophelia le Jenna ba nang natso ke 64+20 = <<64+20=84>>84 
Fa ba kopane, ba na le disofa di le 84 le ditilo di le 88  = <<84+88=172>>172
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Ada's weekly electric consumption before adding the new device is 12 x 7 = <<12*7=84>>84.
So, her weekly electric bill is 84 x $1.50 = $<<84*1.5=126>>126.
Ada's daily electric consumption after adding the new device is 12 + 2 = <<12+2=14>>14.
So her weekly electric consumption after adding the new device is 14 x 7= <<14*7=98>>98 kilowatts per hour.
Ada's new electric bill per week will be 98 x $1.50 = $<<98*1.5=147>>147
Therefore, the difference between the bill before and after she adds the new device is $147 - $126 = $<<147-126=21>>21.
#### 21