`81^(a//log_(5)3)+27^(log_(9)36)+3^(4//log_(7)9)`
`=(3^(4))^(log35)+(3^(3))^(log_(3^(2))(6^(2)))+3^(4log_(9)7`
`=3^(log_(3)5^(4))+(3^(3))^(log^(3)(6))+3^(4log_(3^(2)7))`
`=5^(4)+3^(log_(3)6^(3))+3^(2log_(3)7)`
`5^(4)+6^(3)+3^(log_(3)7^(2))`
`=625+216+7^(2)`
=890