There’s a pattern to this and I’ll explain in the comments if you want to know or can’t figure it out :)
1.) 27/x^3
2.) a^8/b^12
3.) 7^36/81 OR 13,841,287,201/81
4.) 256m^20/n^4
5.) x^6y^6
6.) 64k^4/k^6
7.) 1,000a^9b^6/a^6b^9
8.) 81x^21/625
9.) 2304/x^16y^12
10.) x^7z^14/y^21
11.) 7,776k^5
12.) x^24y^24/4,096
Hope it’s all helped
The number of rows = 80
number of seats in 1 row = 50
total number of seats is the product of the number of rows and number of seats per row = 80*50 = 4000

$=(a^2-10a)-(b^2+6b) +16$
$=[(a^2-2(5)a+25)-25]-[(b^2+2(3)b+9)-9]+16$
$=(a-5)^2-25-(b+3)^2+9+16$
$=(a-5)^2-(b+3)^2$