A circuit to convert 4-bit Gray numbers to BCD
The Answer requires;


Binary to Gray  ( correct your errors)
4 bit Gray to 5 bit BCD or  {B8=0,B7=0,B6=0,B5}{B4,B3,B2,B1} 
5 bit BCD in 5 Karnaugh Maps then reduce each
5 Maps to 5 logic symbol circuits to complete design, 1 for each 5 bit gray,


Perhaps 10/20 is generous.