180 °- 121°
= 59°
the answer is 59°
Answer:
m=2
Step-by-step explanation:
Not addition, since

and 0 doesn't belong to the set.
Not subtraction, since

.
It is closed under multiplication. The set appears to contain all non-zero multiples of 3.
Not division, since dividing some of the numbers results in rationals which do not belong to the set.
What other operations are you supposed to consider?