You (or your homework sheet) may be fishing for the answer "connect
the 3 resistors in parallel", but that does not do the job.
When those 3 resistors are connected in parallel, their combined resistance
is 6/11 ohm.
If the 2 and the 3 alone are in parallel, their combination is 6/5 ohms, and
adding the 1 ohm in series makes 2.2 ohms.
If the 1 and the 2 alone are in parallel, their combination is 2/3 , and adding
the 3 in series makes 3 and 2/3 .
If the 1 and the 3 alone are in parallel, their combination is 3/4 , and adding
the 2 in series makes 2.75 .
There is nothing you can do with those 3 resistors, or with any 2 of them,
or with any 1 of them, that will give you 5/6 ohm .
