The union of the sets are the values that appear in both sets when plotted in a Venn diagram and if I'm not mistaking, I think the right answer is (B)
The answer to your question is C.
8a+4s=840
a=s+30
8(s+30)+4s=840
12s+240=840
12s=600
s=50
A=s+30
a=50+30
a=80
The drama play sold 80 adult tickets
h(x)=-8x+360
-360
h (x)= -8x
sorry if that is incorrect