7. a) A combinational circuit is defined by the following functions F1(x,y,z)=yzx+ yz'x+ y'z'x'+yzx" F2(z,x,y)=11(0,1,3,4,6) Design the circuit using one 3 to 8 decoder and 2 NOR gates. b) Design a 1-bit full subtractor using one 3 to 8 decoder and 2 OR gates