2 forces pull horizontally on a heavy box. force b is directed 20 west of north and pulls twice as hard as force a. the resultant of these two pulls is 400N directly northward. using vector components to show two possible solutions to this problem:

Question

2 forces pull horizontally on a heavy box. force b is directed 20 west of north and pulls twice as hard as force a. the resultant of these two pulls is 400N directly northward. using vector components to show two possible solutions to this problem: 
a. what are the two possible magnitudes of force b?
b. what are the two possible magnitudes and directions of force a?
which solution is more sensible and why