The value of the new machine is RMB 11,000, the salvage value is RMB 900, and the service life is 100 years, if set;

 BVS L- the book value of straight line depreciation at the end of t

 BVS D- book value of depreciation by summation of years at the end of t

 What is the maximum value of t for BVSL-BVS D?