Answer
$a=21.6$
$b=19.32$
$c=6.36$
Work Step by Step
Let's find the angle opposite to b:
$B=180°-102.4°-16.7°=60.9°$
$\frac{b}{sin~60.9°}=\frac{21.6}{sin~102.4°}$
$b=21.6\frac{sin~60.9°}{sin~102.4°}=19.32$
$\frac{c}{sin~16.7°}=\frac{21.6}{sin~102.4°}$
$c=21.6\frac{sin~16.7°}{sin~102.4°}=6.36$
