Given vectors u and v, find (a) 2u (b) 2u +6v (c) v-6u. u =7i, v = 3i + 8j (a) 2u = (Type your answer in terms of i and j.) (b) 2u + 6v = (Type your answer in terms of i and j.) (c) v - 6u = (Type your answer in terms of i and j.)