find a ! please :))))

Answer:
21.8 cm
Step-by-step explanation:
[tex] \\ 180 - 75 - 31.8 = 37.2 \\ \frac{ \sin(75) }{22} = \frac{ \sin(31.8) }{12} = \frac{ \sin(73.2) }{a} \\ a = \frac{22 \times \sin(73.2) }{ \sin(75) } = \\ a = \frac{21.06}{0.9659} = 21.8[/tex]