#1**+2 **

Using the Law of Sines to find the angle opposite the side of 15, we have

arcsin [ 15*sin (108) / 28 ] ≈ 30.63°

So...the remaining agle must be = 180 - 108 - 30.63 ≈ 41.37°

So......applying the Law of Sines once more, we have

x / sin (41.37) = 28 / sin (108) ...... multiply both sides by sin (41.37)

x = 28* sin( 41.37) / sin (108) ≈ 19.46

CPhill Sep 27, 2017