The diagram below shows part of a circuit:

If this arrangement of three resistors was to be placed by a single resistor, its resistance should be :

the two 6 Ω resistors are in parallel. Hence, the Equivalent Resistor =

Now, 3 Ω and 6 Ω resistors are in series. Hence the Total Equivalent Resistance = 3 + 6 = 9 Ω