Answer:
So the answer is both
180 and 328 (but it may or may not show you "not possible, if so, then you got it right)
Explanation:
SinA/a= SinB/b
1. SinM/780 = Sin164/760
2. 780sin164/760 = 0.2828909704
3. M = sin^-1 (0.2828909704)= 16.4328229 or 16
Check for possibility
180-16= 164
164 + 16= 180 (not possible)
164 + 164= 328 (not possible)