73.
1) =4^(2n+3n-1+n+2)=4^(6n+1)
2) =x^(n+2+5+4n-1)=x^(5n+6)
3) = 6^(n+3+2n-1+3n)=6^(6n+2)
4) =a^(7+2n+3n-2)=a^(5n+5)
5) =5^(3n+4+2n-1+n+2)=5^(6n+5)
6) =a^(6n-7+4n-1-(5n-2))=a^(10n-8-5n+2)=a^(5n-6)
7) = 3^(4n+3+3n-2-(2n-1))=3^(7n+1-2n+1)=3^(5n+2)
8) =b^(5n-9+3n+2-(4n-1))=b^(8n-7-4n+1)=b^(4n-6)