I think the answer would be C. (btw, you should charge your phone/tablet, lol)
200 * 33/40 = 165 owns phones
165 * 10/11 = 150 owns phones and MP3 player
Therefore 3/4 owns both and
165 owns only phones
Estimation:
23 --> rounded to 20
71 --> rounded to 70
70 + 20 = 90. I rounded both numbers down so the exact sum must be only a little greater than my estimate.