The Law of Sines tells you
... sin(C)/c = sin(A)/a
... sin(C) = c·sin(A)/a . . . . multiply by c
... C = arcsin(c·sin(A)/a) . . take the inverse sine
Then
... sin(B)/b = sin(A)/a . . . . law of sines again
... b = a·sin(B)/sin(A) . . . . multiply by a·b/sin(A)
where B = 180° - A - C = 160° - C . . . . . . sum of angles in a triangle is 180°
Filling in the given values, we get
... C = arcsin(5.4·sin(20°)/3.3) ≈ 34.033° or 145.967°
Then
... B = 125.967° or 14.033°
and
... b = 3.3/sin(20°)·sin(125.967°) or 3.3/sin(20°)·sin(14.033°)
... b = 7.8 or 2.3 . . . units
The appropriate choice is
... 2.3 units and 7.8 units
