I found this circuit in a textbook, but I'm having a difficult time calculating the total resistance here. I tried using the formula for parallel resistors with the 3 resistors the the upper left, and then add that to the most right resistors. This would give me the total resistance of the upper half of the circuit. I then used that resistance, and used the formula for parallel circuits with the lower portion, but that gave me an incorrect answer.
The solution is supposedly 10ohm / 11.