thank you all for your answers and guidelines , as I studied Behzad Razavi CMOS design book , I have written one voltage division on R2 from Vref and then written one KVL in the loop between R2 and Vgs of the Q2 and finally calculated the current flowing through the Q2 , I don't know if it is the correct approach or not , because as I know , there is no element between transistor pairs of a current mirror and according to CMOS design book of Mr. Razavi , if there is any element between two transistor pairs of current mirror, then we cannot call it a current mirror because the current which is flowing through Q2 won't copy the reference current.
Thank you all