You have formed a band despite advice to the contrary. Actualy the band is pretty good except for the fact the lead singer (who owns the the drum set the microphones and the garage where you practice) is a bit tone deaf. Design a circuit that takes the output from each of the five microphones your band uses and adds the voltage to create a single voltage signal which is fed to the amplifer. Except not all voltages should be equaly amplified. One microphone output should be attenuated such that its peak voltage is 10% of any other microphone's peak voltage.