If the sales matrices for January and March (with twice as many cars of each model sold in February as January) had been

.[1 0 0], and [2 1 0]

.[4 2 3]........[6 1 4] respectively, find the sales matrix for the first quarter of the year.

I figured that the quarter year sales would be 2*January + March = [4 .1.. 0]

.................................................. .........................................[14 5 10]

However, the answers give the answer [5 ..1 ..0]

.................................................. ...[18 7 13], why is this?