How many Selectors with how many inputs and how many select

How many Selectors with how many inputs and how many select lines would be necessary to properly chose one of 27 devices (Dev0 to Dev26) where each dev ice had 45 outputs (Z0 to Z44) ? Selectors. Inputs; Sel Lines: What signal would be connected to the third input (12) of selector four ($3) ? Dev = Output = List four steps required to create good solder joints for through hole components

Solution

9) A. Clean component leads and PCB printed circuit board

B. Clean the soldering iron tip by applying temperature and wipe with a sponge

C. Melt small solder onto iron tip(Tin the iron tip) to enable heat transfer to joint to be soldered.

D. Apply solder so as to tin the pads using a solder wick to release it