Order processing time

An order moves between states Queued, Working and Done once per step. From Queued: stay Queued with probability $\frac{1}{4}$, go to Working with probability $\frac{1}{2}$, go to Done with probability $\frac{1}{4}$. From Working: go back to Queued with probability $\frac{1}{3}$, stay Working with probability $\frac{1}{3}$, go to Done with probability $\frac{1}{3}$. Done is final. An order starts Queued. What is the expected number of steps until it is Done? Give a fraction a/b in lowest terms.

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