GMAT Problem Solving (PS) | Re: A retail appliance store priced a video recorder at 20 percent above

So here, basically we are increasing a number first by 20%, and then decreasing it by 10%. So lets say we start with 100.
Increase 100 by 20% = 120
Decrease 120 by 10% = 120-12 = 108

If you start with 100, you end at 108 (overall 8% increase)
If you start with 200 (double of 100), you will end at 216 (double of 108)

Hence B

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