ease of sn1 reaction:

C6H5CH2Br AND (C6H5)2CHBr

Sn1 reaction is a first order reaction which depends on the stability of the carbocation.More stable the carbocation more will be the tendency to have Sn1 reaction.
here SN1 reaction of C6H5CH2Br AND (C6H5)2CHBr will produce two carbocation C6H5CH2+ and (C6H5)2CH+.The stability of 2 degree carbocation is more as compared to 1 degree carbocation.Out of these two carbocation(C6H5)2CH+ is more stable thanC6H5(CH3)CH+ because the carbocation(C6H5)2CH+ is resonance stabilized by two benzene ringsTherefore
ease of sn1 is C6H5CH2Br < (C6H5)2CHBr