We know that it can't be B. or C. since it has to be greater than 150, so (I know this isn't the way to do it) bet is you try multiplying your leftover answers you have by .3 you would see that 200 times .3 is 60, so that isn't it but 500 times .3 is 150!
The centroid is the average of the coordinates of the three vertices. If you know two vertices (A and B) and the centroid (Q), then the third vertex (C) is ...
