two planes A and B are flying at the same height. A is travelling at 500 km hr^-1 in a westerly direction. B is travelling at 600 km hr^-1 in a north westerly direction. a third plane C is also flying at the same flying at the same height appears to pilot A to be flying in a north west direction. whereas to the pilot of B plane C appears to be flying in a direction 30 degrees south of west. find the magnitude and direction of the true velocity of plane C

i have tried solving this using the 2 formula Vca=Vc-Va and Vcb=Vc-Vb but there are too many variables.