Looking at it simply: On the basis that Vo is not required to supply current, the resistor is irrelevant to your calculations. Since Vo is electrically tied to Vi then Vo is always equal to Vi.
This, of course assumes the output impedance of Vi is zero. In reality, if Vi output port has impedance, let us call it Vi(imp), when set low, then the value at Vo will be the algebraic solution of the potential divider set up by your 2490 resistor in series with Vi(imp) and the actual value of Vi(low).
Similarly the value of Vo, with Vi set high, will be dependant upon the actual value of Vi(high) and the impedance of its output when set high.