Reducing the rental cost by a factor of 6 makes it be 90%/6 = 15% of the original costs of the company. The non-rental costs are 100% -90% = 10% of the original costs of running the company.
Now, the rental costs are 15%/(15%+10%) = 3/5 of the present costs of the company.
Rental cost constitutes 60% in the total costs of the company.
