First, drag and drop the built in PAGE_NUMBER variable twice onto your report. Make sure the height of the field box is tall enough by right-clicking and selecting Properties > Common > Height. The height of a box must be at least 3 pixels higher than the font size. It must be at least 4 pixels higher if the font size is bold.
Format the first (left) box’s expression to look like this:
Right-click the left box and select Properties > All > and scroll down to Eval. Time. Select Page. Still in Properties, navigate to the Font tab. Select Right for Horizontally Align.
Do not edit the second (right) box’s expression. Right-click and open Properties. Set its Eval. Time to Report. Set its Horizontally Align option to Left.
Your report should look like this when you’re done.