Answer:
$41
Step-by-step explanation:
So,
[tex]a_1=\$68\\ \\a_2=\$65\\ \\a_3=\$62\\ \\...[/tex]
where [tex]a_n[/tex] is the rate per nth room rented.
This is an arithmetic sequence, so
[tex]a_n=a_1+(n-1)\cdot d[/tex]
In your case,
[tex]a_1=68\\ \\n=10\\ \\d=-3[/tex]
Hence
[tex]a_{10}=68+(10-1)\cdot (-3)=68-9\cdot 3=68-27=41[/tex]
This means if a group rents 10 rooms, the charge per room is $41.