What is EWB: a circuit theorem, or perhaps a software package? Normally we would ask for some effort at a solution on your part, but perhaps tonight I will make an exception.
This could be done with an ordinary spreadsheet, writing expressions for the upper and lower parts of the potential divider:
The upper part R1 is the remaining part of the potentiometer track; R1 = (Rd-RX).
The lower part R2 is the parallel combination of RL andRX ; R2 = (RL*RX)/(RL+RX).
The potential divider expression will do the rest. If you don't know it, Google it.
Since this is a homework assignment, we can not simply give you the answer. We need to see what you have done so far, and we can help you with it from there. We won't do all the work ourselves