Question

It says to solve I don't remember much about doing logs

Answer 1

Remember
$log_{b}m^{n}=nlog_{b}m$

$1/4log_{5}81=log_{5}81^{1/4}=log_{5}3$
$1/2log_{5}64=log_{5}64^{1/2}=log_{5}8$

we now have
$log_{5}n=log_{5}3+log_{5}8$
remember
$log_{b}m+log_{b}n= log_{b}(mn)$ so
$log_{5}3+log_{5}8= log_{5}(3*8)=log_{5}24$
$log_{5}n=log_{5}24$
therefor n=24