I don't know how to solve part b could you help me with it

Problem 2 (20 points; 10 points each): (a) Design a combinational circuit that accepts a 3-bit input XXXo and produces an output Y that represents the number of l's in the 3-bit input X. Show the truth table of the circuit. ) Design a combinational circuit that receives a 6-bit input X-XsX4XsX2XiXo and produces arn output Y that represents the number of l's in X. Design the required circuit using as many of the 3- bit l's count circuit designed in part (a) as needed, and minimum number of needed half and full adders. Show the circuit implementation (no need to show the internal circuit of the 3-bit 1's count circuit designed in part (a))