.
(1)  Calculate the magnitude of vector (q)  
     |q| = 
 = 
 = 
 = 3.5.
(2)  Notice that the magnitude of vector (r), 10.5, is three times 
     the magnitude of vector {q), 3.5.
(3)  With the condition of parallelity, it means that each components of vector 
     {r) is three times the corresponding component of vector (q).
     So,  (r) = (9i) - (3j) + (4.5k).      ANSWER
Solved.