Answer the following problems as neatly as possible.

Three different microphones are used in the recording studio, namely: one for vocals, one for guitar and one for piano. Design the circuits using op$-$amps of the following scenario:

a$.$ An op$-$amp circuit that will allow the microphones for guitar and piano outputs to be combined but with the vocals receiving thrice the amplification as with the instruments.

b$.$ An op$-$amp circuit that will only output the microphone for the vocals and cancel out the output of the instruments.

Marking Scheme:

Calculations $1$ Mark

Simulation $1$ Mark