Question

show how would you join the three resistors each of resistance 9 ohm so that the equivalent resistance of the combination is 13.5 and 6 ohms

Answer 1

TO GET AN EFFECTIVE RESISTENCE OF 13.5 OHM, THE TWO RESOSTORS MUST BE CONNECTED IN PARALLEL AND ONE IN SERIES.
TO GET AN EFFECTIVE RESISTENCE 6 OHM, WE NEED TO CONNECT TWO RESISTORS IN SERIES AND ONE IN PARALLEL