80x20=1600 costumes
12x90=1080 masks
1600-1080=520
they ordered 520 more costumes than masks. hope this helps!
I wrote it for you because i didnt know how to write it out in a way that made sense
hope this works! xx
Answer: 
Step-by-step explanation:

7+z / 2
z = 10
replace the value of z
7 +10 /2
use order of operations ( division comes before addition)
7+5 = 12
Answer:
=64 %
Step-by-step explanation:
The percentage decrease is found by
Percent decrease = (original - new)/ original * 100 percent
The original price is 25
The new price is 9
Percent decrease = (25-9)/25 * 100%
=16/25 * 100%
=64 %