help me guys

Question

s={10,20,30}
t={3,4}
u=s.union_update(t)
print (u)

Answer 1

a = {10,20,30}
b = {3,4}
a.update(b)
print(a)

Its a right way to union both the set

Answer 2

Instead of "u=s.union_update(t)"
use:
u = s.union(t)

Answer 3

How about:
print(a|b)