Step-by-step explanation:
Use the sine rule.
[tex] \frac{ \sin(a) }{12} = \frac{ \sin(42) }{22} [/tex]
Rearrange to get a as the subject
[tex]x = { \sin}^{ - 1} ( \frac{ \sin(42) }{22} \times 12)[/tex]
[tex]x = 21.4[/tex]
