Let us first find the Boolean expression for logic circuit (a) So, above logic circuit provides output as OR gate. Here X = $\overset{\text{----------}}{{A+B}}$ and Y = $\overset{-}{X}$ = $\left(\overset{\text{----------}}{{\overset{\text{----------}}{A+B}}}\right)$ = A + B Now let us find the Boolean expression for logic circuit (b) By De-Morgan’s theorem we know , $\left(\overset{\text{----------}}{{\overset{-}{A}+\overset{-}{B}}}\right)$ = AB So, above logic circuit provides output as AND gate.